21725164 has 6 divisors (see below), whose sum is σ = 38019044. Its totient is φ = 10862580.

The previous prime is 21725161. The next prime is 21725183. The reversal of 21725164 is 46152712.

It is not an unprimeable number, because it can be changed into a prime (21725161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2715642 + ... + 2715649.

Almost surely, 2^21725164 is an apocalyptic number.

It is an amenable number.

21725164 is a deficient number, since it is larger than the sum of its proper divisors (16293880).

21725164 is a wasteful number, since it uses less digits than its factorization.

21725164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5431295 (or 5431293 counting only the distinct ones).

The product of its digits is 3360, while the sum is 28.

The square root of 21725164 is about 4661.0260672946. The cubic root of 21725164 is about 279.0322200856.

Adding to 21725164 its reverse (46152712), we get a palindrome (67877876).

The spelling of 21725164 in words is "twenty-one million, seven hundred twenty-five thousand, one hundred sixty-four".