21539164 has 12 divisors (see below), whose sum is σ = 38148264. Its totient is φ = 10639664.

The previous prime is 21539149. The next prime is 21539183. The reversal of 21539164 is 46193512.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 32107 + ... + 32770.

It is an arithmetic number, because the mean of its divisors is an integer number (3179022).

Almost surely, 2^21539164 is an apocalyptic number.

It is an amenable number.

21539164 is a deficient number, since it is larger than the sum of its proper divisors (16609100).

21539164 is a wasteful number, since it uses less digits than its factorization.

21539164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64964 (or 64962 counting only the distinct ones).

The product of its digits is 6480, while the sum is 31.

The square root of 21539164 is about 4641.0304890186. The cubic root of 21539164 is about 278.2336251873.

The spelling of 21539164 in words is "twenty-one million, five hundred thirty-nine thousand, one hundred sixty-four".