21665038 has 16 divisors (see below), whose sum is σ = 34719840. Its totient is φ = 10103296.

The previous prime is 21665009. The next prime is 21665041. The reversal of 21665038 is 83056612.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 1023 + ... + 6661.

It is an arithmetic number, because the mean of its divisors is an integer number (2169990).

Almost surely, 2^21665038 is an apocalyptic number.

21665038 is a deficient number, since it is larger than the sum of its proper divisors (13054802).

21665038 is a wasteful number, since it uses less digits than its factorization.

21665038 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5771.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 21665038 is about 4654.5717311048. The cubic root of 21665038 is about 278.7745681390.

The spelling of 21665038 in words is "twenty-one million, six hundred sixty-five thousand, thirty-eight".