21086636 has 12 divisors (see below), whose sum is σ = 37282728. Its totient is φ = 10434432.

The previous prime is 21086623. The next prime is 21086671. The reversal of 21086636 is 63668012.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26786 + ... + 27561.

It is an arithmetic number, because the mean of its divisors is an integer number (3106894).

Almost surely, 2^21086636 is an apocalyptic number.

It is an amenable number.

21086636 is a deficient number, since it is larger than the sum of its proper divisors (16196092).

21086636 is a wasteful number, since it uses less digits than its factorization.

21086636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54448 (or 54446 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 21086636 is about 4592.0187281848. The cubic root of 21086636 is about 276.2712973350.

The spelling of 21086636 in words is "twenty-one million, eighty-six thousand, six hundred thirty-six".