21665036 has 12 divisors (see below), whose sum is σ = 38556840. Its totient is φ = 10648800.

The previous prime is 21665009. The next prime is 21665041. The reversal of 21665036 is 63056612.

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, 45665 + ... + 46136.

It is an arithmetic number, because the mean of its divisors is an integer number (3213070).

Almost surely, 2^21665036 is an apocalyptic number.

It is an amenable number.

21665036 is a deficient number, since it is larger than the sum of its proper divisors (16891804).

21665036 is a wasteful number, since it uses less digits than its factorization.

21665036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91864 (or 91862 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 21665036 is about 4654.5715162623. The cubic root of 21665036 is about 278.7745595606.

The spelling of 21665036 in words is "twenty-one million, six hundred sixty-five thousand, thirty-six".