21625945 has 16 divisors (see below), whose sum is σ = 29078208. Its totient is φ = 15301440.

The previous prime is 21625939. The next prime is 21625949. The reversal of 21625945 is 54952612.

It is a happy number.

It is not a de Polignac number, because 21625945 - 2⁵ = 21625913 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21625945.

It is not an unprimeable number, because it can be changed into a prime (21625949) 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, 3279 + ... + 7348.

It is an arithmetic number, because the mean of its divisors is an integer number (1817388).

Almost surely, 2^21625945 is an apocalyptic number.

It is an amenable number.

21625945 is a deficient number, since it is larger than the sum of its proper divisors (7452263).

21625945 is a wasteful number, since it uses less digits than its factorization.

21625945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10680.

The product of its digits is 21600, while the sum is 34.

The square root of 21625945 is about 4650.3704153540. The cubic root of 21625945 is about 278.6067909775.

The spelling of 21625945 in words is "twenty-one million, six hundred twenty-five thousand, nine hundred forty-five".