20631905 has 16 divisors (see below), whose sum is σ = 29272320. Its totient is φ = 13659072.

The previous prime is 20631899. The next prime is 20631907. The reversal of 20631905 is 50913602.

It is not a de Polignac number, because 20631905 - 2⁸ = 20631649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20631907) 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, 9149 + ... + 11178.

It is an arithmetic number, because the mean of its divisors is an integer number (1829520).

Almost surely, 2^20631905 is an apocalyptic number.

It is an amenable number.

20631905 is a deficient number, since it is larger than the sum of its proper divisors (8640415).

20631905 is a wasteful number, since it uses less digits than its factorization.

20631905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20368.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 20631905 is about 4542.2356830090. The cubic root of 20631905 is about 274.2709283195.

The spelling of 20631905 in words is "twenty million, six hundred thirty-one thousand, nine hundred five".