Properties of the Number 31815

Thirty-One Thousand Eight Hundred Fifteen

Basics

Value: 31814 → 31815 → 31816

Parity: odd

Prime: No

Previous Prime: 31799

Next Prime: 31817

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 5 × 7 × 101

Divisors: 1, 3, 5, 7, 9, 15, 21, 35, 45, 63

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 111110001000111

Octal: 76107

Duodecimal: 164B3

Hexadecimal: 7c47

Square: 1012194225

Square Root: 178.367597954337

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

Numbers k whose abundance is 18: σ(k) - 2·k = 18. A223610

Numbers k such that σ(k) = σ(k+3). A15861

Odd numbers whose abundancy is closer to 2 than any smaller odd number. A171929

Odd numbers n such that abs(σ(n)-2n) <= n^1/3. Abundance-radius = abs(σ(n)-2n) does not exceed cubic root of n and n is odd. A88010

Odd abundant numbers whose abundancy is closer to 2 than any smaller odd abundant number. A188263

Numbers k such that σ(k) == 0 (mod k+9). A274563

Odd admirable numbers: such that σ(n) = 2n + 2d for some d | n. A109729

Odd numbers k that are closer to being perfect than previous terms and also satisfy the conditions that σ(k) preserves the 3-adic valuation of k, and that σ(k) == -k (mod 3). A386420

Numbers k such that φ(k)=p², where p is product of digits of k. A153427

Irregular triangle read by rows where row n lists all odd primitive abundant numbers with n prime factors, counted with multiplicity. A287646