21664712 has 32 divisors (see below), whose sum is σ = 44625600. Its totient is φ = 9814464.

The previous prime is 21664703. The next prime is 21664717. The reversal of 21664712 is 21746612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664717) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 398 + ... + 6594.

It is an arithmetic number, because the mean of its divisors is an integer number (1394550).

Almost surely, 2^21664712 is an apocalyptic number.

It is an amenable number.

21664712 is an abundant number, since it is smaller than the sum of its proper divisors (22960888).

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

21664712 is a wasteful number, since it uses less digits than its factorization.

21664712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6245 (or 6241 counting only the distinct ones).

The product of its digits is 4032, while the sum is 29.

The square root of 21664712 is about 4654.5367116395. The cubic root of 21664712 is about 278.7731698652.

The spelling of 21664712 in words is "twenty-one million, six hundred sixty-four thousand, seven hundred twelve".