21039516 has 36 divisors (see below), whose sum is σ = 54191592. Its totient is φ = 6880224.

The previous prime is 21039493. The next prime is 21039521. The reversal of 21039516 is 61593012.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21039516² = 885322467028512, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21039516.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3606 + ... + 7421.

It is an arithmetic number, because the mean of its divisors is an integer number (1505322).

Almost surely, 2^21039516 is an apocalyptic number.

It is an amenable number.

21039516 is an abundant number, since it is smaller than the sum of its proper divisors (33152076).

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

21039516 is a wasteful number, since it uses less digits than its factorization.

21039516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11090 (or 11085 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 21039516 is about 4586.8852176613. The cubic root of 21039516 is about 276.0653594423.

The spelling of 21039516 in words is "twenty-one million, thirty-nine thousand, five hundred sixteen".