21660631 has 8 divisors (see below), whose sum is σ = 22186224. Its totient is φ = 21141120.

The previous prime is 21660619. The next prime is 21660637. The reversal of 21660631 is 13606612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21660631 - 2²³ = 13272023 is a prime.

It is a super-2 number, since 2×21660631² = 938365870636322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21660596 and 21660605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6141 + ... + 9001.

It is an arithmetic number, because the mean of its divisors is an integer number (2773278).

Almost surely, 2^21660631 is an apocalyptic number.

21660631 is a deficient number, since it is larger than the sum of its proper divisors (525593).

21660631 is a wasteful number, since it uses less digits than its factorization.

21660631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3041.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21660631 is about 4654.0983014973. The cubic root of 21660631 is about 278.7556645205.

The spelling of 21660631 in words is "twenty-one million, six hundred sixty thousand, six hundred thirty-one".