20951 has 8 divisors (see below), whose sum is σ = 24864. Its totient is φ = 17280.

The previous prime is 20947. The next prime is 20959. The reversal of 20951 is 15902.

20951 = 21² + 22² + ... + 41².

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20951 - 2² = 20947 is a prime.

It is an Ulam number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20951.

It is not an unprimeable number, because it can be changed into a prime (20959) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 251 + ... + 323.

It is an arithmetic number, because the mean of its divisors is an integer number (3108).

2²⁰⁹⁵¹ is an apocalyptic number.

20951 is a deficient number, since it is larger than the sum of its proper divisors (3913).

20951 is an equidigital number, since it uses as much as digits as its factorization.

20951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121.

The product of its (nonzero) digits is 90, while the sum is 17.

The square root of 20951 is about 144.7446026628. The cubic root of 20951 is about 27.5677667532.

The spelling of 20951 in words is "twenty thousand, nine hundred fifty-one".