21620907 has 36 divisors (see below), whose sum is σ = 39640536. Its totient is φ = 11229120.

The previous prime is 21620903. The next prime is 21620927. The reversal of 21620907 is 70902612.

It is not a de Polignac number, because 21620907 - 2² = 21620903 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21620903) 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 35 ways as a sum of consecutive naturals, for example, 2623 + ... + 7079.

It is an arithmetic number, because the mean of its divisors is an integer number (1101126).

Almost surely, 2^21620907 is an apocalyptic number.

21620907 is a deficient number, since it is larger than the sum of its proper divisors (18019629).

21620907 is a wasteful number, since it uses less digits than its factorization.

21620907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4488 (or 4478 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21620907 is about 4649.8287065224. The cubic root of 21620907 is about 278.5851544660.

The spelling of 21620907 in words is "twenty-one million, six hundred twenty thousand, nine hundred seven".