Properties of the Number 1557

One Thousand Five Hundred Fifty-Seven

Basics

Value: 1556 → 1557 → 1558

Parity: odd

Prime: No

Previous Prime: 1553

Next Prime: 1559

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 173

Divisors: 1, 3, 9, 173, 519, 1557

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 11000010101

Octal: 3025

Duodecimal: A99

Hexadecimal: 615

Square: 2424249

Square Root: 39.45883931389772

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

Odd numbers of the form p^1+4k * r², where p is prime of the form 1+4m, r > 1, and gcd(p,r) = 1. (Euler's criteria for odd perfect numbers). A228058

Triangle T(n,k) read by rows, giving number of graphs with n nodes (n >= 1) and k edges (0 <= k <= n(n-1)/2). A8406

Coordination sequence for 3D uniform tiling formed by stacking parallel layers of the 3⁴.6 2D tiling (cf. A250120). A299254

Partial sums of A299279. A299280

a(n) = ∑_{k divides n} (n/k)^k. A55225

a(n) = n² + 3·n - 1. A14209

Triangle read by rows: T(n,k) = (4n-4k+1) * T(n-1,k-1) + (4k-3) * T(n-1,k). A142459

Numbers that are the sum of 3 nonzero squares in exactly 10 ways. A25330

Numbers where 5 outnumbers any other digit. A292455

Numbers k whose largest divisor <= sqrt(k) equals 9. A162529