21641625 has 24 divisors (see below), whose sum is σ = 39014664. Its totient is φ = 11541600.

The previous prime is 21641611. The next prime is 21641671. The reversal of 21641625 is 52614612.

It can be written as a sum of positive squares in 4 ways, for example, as 3697929 + 17943696 = 1923^2 + 4236^2 .

It is not a de Polignac number, because 21641625 - 2⁸ = 21641369 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8494 + ... + 10743.

It is an arithmetic number, because the mean of its divisors is an integer number (1625611).

Almost surely, 2^21641625 is an apocalyptic number.

21641625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21641625 is a deficient number, since it is larger than the sum of its proper divisors (17373039).

21641625 is a wasteful number, since it uses less digits than its factorization.

21641625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19258 (or 19245 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21641625 is about 4652.0559970834. The cubic root of 21641625 is about 278.6741097944.

The spelling of 21641625 in words is "twenty-one million, six hundred forty-one thousand, six hundred twenty-five".