640978773 has 16 divisors (see below), whose sum is σ = 874022400. Its totient is φ = 417709040.

The previous prime is 640978771. The next prime is 640978777. The reversal of 640978773 is 377879046.

640978773 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 640978773 - 2¹ = 640978771 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640978771) 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, 21568 + ... + 41798.

It is an arithmetic number, because the mean of its divisors is an integer number (54626400).

Almost surely, 2^640978773 is an apocalyptic number.

It is an amenable number.

640978773 is a deficient number, since it is larger than the sum of its proper divisors (233043627).

640978773 is a wasteful number, since it uses less digits than its factorization.

640978773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20472.

The product of its (nonzero) digits is 1778112, while the sum is 51.

The square root of 640978773 is about 25317.5585908278. The cubic root of 640978773 is about 862.2129652727.

The spelling of 640978773 in words is "six hundred forty million, nine hundred seventy-eight thousand, seven hundred seventy-three".