21164025 has 24 divisors (see below), whose sum is σ = 36515520. Its totient is φ = 10795840.

The previous prime is 21163999. The next prime is 21164029. The reversal of 21164025 is 52046112.

It is not a de Polignac number, because 21164025 - 2⁵ = 21163993 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21163992 and 21164010.

It is not an unprimeable number, because it can be changed into a prime (21164029) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4410 + ... + 7859.

It is an arithmetic number, because the mean of its divisors is an integer number (1521480).

Almost surely, 2^21164025 is an apocalyptic number.

21164025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21164025 is a deficient number, since it is larger than the sum of its proper divisors (15351495).

21164025 is a wasteful number, since it uses less digits than its factorization.

21164025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12305 (or 12300 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21164025 is about 4600.4374791970. The cubic root of 21164025 is about 276.6088611672.

The spelling of 21164025 in words is "twenty-one million, one hundred sixty-four thousand, twenty-five".