20640671261 has 48 divisors (see below), whose sum is σ = 26858381760. Its totient is φ = 15717542400.

The previous prime is 20640671251. The next prime is 20640671281. The reversal of 20640671261 is 16217604602.

It is not a de Polignac number, because 20640671261 - 2¹⁴ = 20640654877 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640671251) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4635086 + ... + 4639536.

It is an arithmetic number, because the mean of its divisors is an integer number (559549620).

Almost surely, 2^20640671261 is an apocalyptic number.

It is an amenable number.

20640671261 is a deficient number, since it is larger than the sum of its proper divisors (6217710499).

20640671261 is a wasteful number, since it uses less digits than its factorization.

20640671261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4794 (or 4787 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 35.

The spelling of 20640671261 in words is "twenty billion, six hundred forty million, six hundred seventy-one thousand, two hundred sixty-one".