21036664 has 16 divisors (see below), whose sum is σ = 43029720. Its totient is φ = 9562080.

The previous prime is 21036647. The next prime is 21036671. The reversal of 21036664 is 46663012.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119439 + ... + 119614.

Almost surely, 2^21036664 is an apocalyptic number.

It is an amenable number.

21036664 is an abundant number, since it is smaller than the sum of its proper divisors (21993056).

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

21036664 is a wasteful number, since it uses less digits than its factorization.

21036664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239070 (or 239066 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 21036664 is about 4586.5743207758. The cubic root of 21036664 is about 276.0528849160.

Adding to 21036664 its reverse (46663012), we get a palindrome (67699676).

The spelling of 21036664 in words is "twenty-one million, thirty-six thousand, six hundred sixty-four".