20631409921 has 16 divisors (see below), whose sum is σ = 21022231104. Its totient is φ = 20245469184.

The previous prime is 20631409919. The next prime is 20631409927. The reversal of 20631409921 is 12990413602.

It is a cyclic number.

It is not a de Polignac number, because 20631409921 - 2¹ = 20631409919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20631409927) 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, 4307490 + ... + 4312276.

It is an arithmetic number, because the mean of its divisors is an integer number (1313889444).

Almost surely, 2^20631409921 is an apocalyptic number.

It is an amenable number.

20631409921 is a deficient number, since it is larger than the sum of its proper divisors (390821183).

20631409921 is a wasteful number, since it uses less digits than its factorization.

20631409921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5280.

The product of its (nonzero) digits is 23328, while the sum is 37.

The spelling of 20631409921 in words is "twenty billion, six hundred thirty-one million, four hundred nine thousand, nine hundred twenty-one".