21500164 has 12 divisors (see below), whose sum is σ = 43000384. Its totient is φ = 9214344.

The previous prime is 21500161. The next prime is 21500177. The reversal of 21500164 is 46100512.

21500164 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21500161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 383904 + ... + 383959.

Almost surely, 2^21500164 is an apocalyptic number.

It is an amenable number.

21500164 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21500164 is a wasteful number, since it uses less digits than its factorization.

21500164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 767874 (or 767872 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21500164 is about 4636.8269322889. The cubic root of 21500164 is about 278.0655953420.

Adding to 21500164 its reverse (46100512), we get a palindrome (67600676).

The spelling of 21500164 in words is "twenty-one million, five hundred thousand, one hundred sixty-four".