21625961 has 16 divisors (see below), whose sum is σ = 25567488. Its totient is φ = 17908800.

The previous prime is 21625951. The next prime is 21625963. The reversal of 21625961 is 16952612.

It is a happy number.

It is not a de Polignac number, because 21625961 - 2¹⁰ = 21624937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21625963) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25931 + ... + 26751.

It is an arithmetic number, because the mean of its divisors is an integer number (1597968).

Almost surely, 2^21625961 is an apocalyptic number.

It is an amenable number.

21625961 is a deficient number, since it is larger than the sum of its proper divisors (3941527).

21625961 is an equidigital number, since it uses as much as digits as its factorization.

21625961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 952.

The product of its digits is 6480, while the sum is 32.

The square root of 21625961 is about 4650.3721356468. The cubic root of 21625961 is about 278.6068596867.

The spelling of 21625961 in words is "twenty-one million, six hundred twenty-five thousand, nine hundred sixty-one".