21855693 has 16 divisors (see below), whose sum is σ = 31167936. Its totient is φ = 13574400.

The previous prime is 21855683. The next prime is 21855697. The reversal of 21855693 is 39655812.

It is not a de Polignac number, because 21855693 - 2⁸ = 21855437 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855697) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3030 + ... + 7272.

It is an arithmetic number, because the mean of its divisors is an integer number (1947996).

Almost surely, 2^21855693 is an apocalyptic number.

It is an amenable number.

21855693 is a deficient number, since it is larger than the sum of its proper divisors (9312243).

21855693 is a wasteful number, since it uses less digits than its factorization.

21855693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4364.

The product of its digits is 64800, while the sum is 39.

The square root of 21855693 is about 4675.0072727216. The cubic root of 21855693 is about 279.5899311971.

The spelling of 21855693 in words is "twenty-one million, eight hundred fifty-five thousand, six hundred ninety-three".