21539712 has 32 divisors (see below), whose sum is σ = 57215880. Its totient is φ = 7179776.

The previous prime is 21539701. The next prime is 21539717. The reversal of 21539712 is 21793512.

It is a tau number, because it is divible by the number of its divisors (32).

It is a self number, because there is not a number n which added to its sum of digits gives 21539712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21539717) 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, 27663 + ... + 28430.

Almost surely, 2^21539712 is an apocalyptic number.

It is an amenable number.

21539712 is an abundant number, since it is smaller than the sum of its proper divisors (35676168).

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

21539712 is an equidigital number, since it uses as much as digits as its factorization.

21539712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56110 (or 56098 counting only the distinct ones).

The product of its digits is 3780, while the sum is 30.

The square root of 21539712 is about 4641.0895272554. The cubic root of 21539712 is about 278.2359847764.

The spelling of 21539712 in words is "twenty-one million, five hundred thirty-nine thousand, seven hundred twelve".