21039216 has 40 divisors (see below), whose sum is σ = 59293824. Its totient is φ = 6375360.

The previous prime is 21039197. The next prime is 21039229. The reversal of 21039216 is 61293012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19396 + ... + 20451.

Almost surely, 2^21039216 is an apocalyptic number.

It is an amenable number.

21039216 is an abundant number, since it is smaller than the sum of its proper divisors (38254608).

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

21039216 is a wasteful number, since it uses less digits than its factorization.

21039216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39869 (or 39863 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 21039216 is about 4586.8525156146. The cubic root of 21039216 is about 276.0640473081.

The spelling of 21039216 in words is "twenty-one million, thirty-nine thousand, two hundred sixteen".