Properties of the Number 399

Three Hundred Ninety-Nine

Basics

Value: 398 → 399 → 400

Parity: odd

Prime: No

Previous Prime: 397

Next Prime: 401

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 3 × 7 × 19

Divisors: 1, 3, 7, 19, 21, 57, 133, 399

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 110001111

Octal: 617

Duodecimal: 293

Hexadecimal: 18f

Square: 159201

Square Root: 19.974984355438178

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

a(n) = n*(n+2) = (n+1)² - 1. A5563

Total number of parts in all partitions of n. Also, sum of largest parts of all partitions of n. A6128

Sphenic numbers: products of 3 distinct primes. A7304

Numbers k such that k! + 1 is prime. A2981

Number of partitions of n into pairwise relatively prime parts. A51424

Number of elements in the set {(x,y): 1 <= x,y <= n, gcd(x,y)=1}. A18805

Flavius Josephus's sieve: Start with the natural numbers; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate. A960

Numerator of 1/4 - 1/n². A61037

Sequence and first differences (A030124) together list all positive numbers exactly once. A5228

Sub-perfect powers: perfect powers (squares, cubes etc., not including 1) minus 1. A45542