Properties of the Number 21401

Twenty-One Thousand Four Hundred One

Basics

Value: 21400 → 21401 → 21402

Parity: odd

Prime: Yes

Previous Prime: 21397

Next Prime: 21407

Digit Sum: 8

Digital Root: 8

Palindrome: No

Factorization: 21401

Divisors: 1, 21401

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101001110011001

Octal: 51631

Duodecimal: 10475

Hexadecimal: 5399

Square: 458002801

Square Root: 146.2908062729849

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

Smallest primitive factor of 10ⁿ - 1. Also smallest prime p such that 1/p has repeating decimal expansion of period n. A7138

Smallest number with reciprocal of period length n in decimal (base 10). A3060

Numerators of coefficients in C(x) where: C(x)^1/2 - S(x)^1/2 = 1 such that C'(x)*S(x)^1/2 = S'(x)*C(x)^1/2 = 2·x*C(x). A299430

Primes p such that the decimal representation of 1/p does not contain every digit 0-9. A187614

Intersection of A251964, A252280 and A252281. A252283

Primes p for which the period length of 1/p is a perfect power, A001597. A128948

Primes dividing numbers k such that k divides the k-th Lucas number A000032(k). A129729

Primes dividing repunits R(10ⁿ) for some n. A178070

Second term of weak prime sextet: p(m)-p(m-1) < p(m+1)-p(m) < p(m+2)-p(m+1) < p(m+3)-p(m+2) < p(m+4)-p(m+3). A54829

Primes p such that x⁵ = 2 has a solution mod p, but x^5² = 2 has no solution mod p. A70182