21539264 has 14 divisors (see below), whose sum is σ = 42742104. Its totient is φ = 10769600.

The previous prime is 21539263. The next prime is 21539267. The reversal of 21539264 is 46293512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 21539264.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21539263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 168212 + ... + 168339.

Almost surely, 2^21539264 is an apocalyptic number.

It is an amenable number.

21539264 is a deficient number, since it is larger than the sum of its proper divisors (21202840).

21539264 is an equidigital number, since it uses as much as digits as its factorization.

21539264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336563 (or 336553 counting only the distinct ones).

The product of its digits is 12960, while the sum is 32.

The square root of 21539264 is about 4641.0412624755. The cubic root of 21539264 is about 278.2340557722.

The spelling of 21539264 in words is "twenty-one million, five hundred thirty-nine thousand, two hundred sixty-four".