640937931 has 4 divisors (see below), whose sum is σ = 854583912. Its totient is φ = 427291952.

The previous prime is 640937917. The next prime is 640937933. The reversal of 640937931 is 139739046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640937931 - 2⁶ = 640937867 is a prime.

It is a super-2 number, since 2×640937931² = 821602862789121522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (640937933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106822986 + ... + 106822991.

It is an arithmetic number, because the mean of its divisors is an integer number (213645978).

Almost surely, 2^640937931 is an apocalyptic number.

640937931 is a deficient number, since it is larger than the sum of its proper divisors (213645981).

640937931 is a wasteful number, since it uses less digits than its factorization.

640937931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213645980.

The product of its (nonzero) digits is 122472, while the sum is 42.

The square root of 640937931 is about 25316.7519836175. The cubic root of 640937931 is about 862.1946520038.

The spelling of 640937931 in words is "six hundred forty million, nine hundred thirty-seven thousand, nine hundred thirty-one".