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Properties of the Number 21256

Twenty-One Thousand Two Hundred Fifty-Six

Basics

Value: 21255 → 21256 → 21257

Parity: even

Prime: No

Previous Prime: 21247

Next Prime: 21269

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 2 3 × 2657

Divisors: 1, 2, 4, 8, 2657, 5314, 10628, 21256

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001100001000

Octal: 51410

Duodecimal: 10374

Hexadecimal: 5308

Square: 451817536

Square Root: 145.79437574886077

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

Number of ordered positive integer solutions (m1, m2, ..., mk) (for some k) to ∑i=1..k mi=n with |mi-mi-1| <= 1 for i = 2 ... k. A34297
Numbers k such that the k-th composition in standard order is an alternating permutation of {1..k} for some k. A349051
Triangle read by rows: T(n,k) is the number of partially labeled rooted trees with n vertices, k of which are labeled, 0 <= k <= n. A8295
Number T(n,k) of set partitions of [n] such that the maximal value of all absolute differences between least elements of consecutive blocks and between consecutive elements within the blocks equals k; triangle T(n,k), n>=0, 0<=k<=max(n-1,0), read by rows. A287416
Number of partially labeled rooted trees with n nodes (4 of which are labeled). A525
Number of cycles for vectors of length n under the Ducci map. A135547
Expansion of ∏i>=1, j>=1, k>=1 (1 - xi·j*k)/(1 + xi·j*k). A321241
a(n) = number of triples (a,b,c) of natural numbers a,b,c <= n with gcd(a,b)=gcd(b,c)=gcd(c,a)=1. A256390
Positive integers that have exactly ten representations of the form 1 + p1 * (1 + p2* ... * (1 + pj)...), where [p1, ..., pj] is a (possibly empty) list of distinct primes. A317400
Numbers k that end with ( sum of digits of k )2. A270343