Properties of the Number 81239

Eighty-One Thousand Two Hundred Thirty-Nine

Basics

Value: 81238 → 81239 → 81240

Parity: odd

Prime: Yes

Previous Prime: 81233

Next Prime: 81281

Digit Sum: 23

Digital Root: 5

Palindrome: No

Factorization: 81239

Divisors: 1, 81239

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10011110101010111

Octal: 236527

Duodecimal: 3B01B

Hexadecimal: 13d57

Square: 6599775121

Square Root: 285.02456034524465

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

Primes p=prime(i) of level (1,5), i.e., such that A118534(i) = prime(i-5). A118464

Primes p such that q-p = 42, where q is the next prime after p. A134120

Primes of the form n² + 14. A243449

Numbers k such that k divides ∑_j=1..k j^k+1-j. A341436

a(n) is the n-th prime of the form x²+n. A128968

#{(i,j): μ(i)*μ(j) = 0, 1<=i,j<=n}, where μ=A008683 (Moebius function). A81239

Algorithm: s(k) = n. s(k+1) = s(k) - digitsum(s(k))² if s(k) >= 0 and s(k+1) = s(k)+digitsum(abs(s(k)))² if s(k) < 0. Below gives the end behavior for each number n. A290223

a(n) = ∑_k=0..n 5^k * 2^n-k * binomial(2·n+k-1,k). A386767