Properties of the Number 9991

Nine Thousand Nine Hundred Ninety-One

Basics

Value: 9990 → 9991 → 9992

Parity: odd

Prime: No

Previous Prime: 9973

Next Prime: 10007

Digit Sum: 28

Digital Root: 1

Palindrome: No

Factorization: 97 × 103

Divisors: 1, 97, 103, 9991

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10011100000111

Octal: 23407

Duodecimal: 5947

Hexadecimal: 2707

Square: 99820081

Square Root: 99.95498987044118

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) = prime(n)*prime(n+2). A90076

Numbers in which 9 outnumbers all other digits together. A292739

Consider all permutations p_i of the first n primes; a(n) is the minimum over p_i of the maximal product of two adjacent primes in the permutation. A332765

Number T(n,k) of blocks of size >= k in all set partitions of [n], assuming that every set partition contains one block of size zero; triangle T(n,k), n>=0, 0<=k<=n, read by rows. A283424

Quasi-Carmichael numbers to exactly two bases. A257752

Product of the n-th sexy prime pair. A111192

Numbers n such that exactly two positive d in the range d <= n/2 exist which divide binomial(n-d-1, d-1) and which are not coprime to n. A178098

Sequence of pairwise relatively prime numbers of class P₄ (see comment in A275246). A275248

Sum T(n,k) of the k-th entries in all blocks of all set partitions of [n]; triangle T(n,k), n>=1, 1<=k<=n, read by rows. A285595

Minimal permanent of an n X n symmetric Toeplitz matrix using the integers 1 to n. A351019