21535916 has 12 divisors (see below), whose sum is σ = 37753632. Its totient is φ = 10749168.

The previous prime is 21535903. The next prime is 21535931. The reversal of 21535916 is 61953512.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1940 + ... + 6843.

It is an arithmetic number, because the mean of its divisors is an integer number (3146136).

Almost surely, 2^21535916 is an apocalyptic number.

It is an amenable number.

21535916 is a deficient number, since it is larger than the sum of its proper divisors (16217716).

21535916 is a wasteful number, since it uses less digits than its factorization.

21535916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9400 (or 9398 counting only the distinct ones).

The product of its digits is 8100, while the sum is 32.

The square root of 21535916 is about 4640.6805535395. The cubic root of 21535916 is about 278.2196390635.

The spelling of 21535916 in words is "twenty-one million, five hundred thirty-five thousand, nine hundred sixteen".