21502164 has 12 divisors (see below), whose sum is σ = 50171744. Its totient is φ = 7167384.

The previous prime is 21502157. The next prime is 21502181. The reversal of 21502164 is 46120512.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21502164.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 895912 + ... + 895935.

Almost surely, 2^21502164 is an apocalyptic number.

It is an amenable number.

21502164 is an abundant number, since it is smaller than the sum of its proper divisors (28669580).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21502164 is a wasteful number, since it uses less digits than its factorization.

21502164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1791854 (or 1791852 counting only the distinct ones).

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

The square root of 21502164 is about 4637.0425919976. The cubic root of 21502164 is about 278.0742171979.

Adding to 21502164 its reverse (46120512), we get a palindrome (67622676).

The spelling of 21502164 in words is "twenty-one million, five hundred two thousand, one hundred sixty-four".