640634677 has 2 divisors, whose sum is σ = 640634678. Its totient is φ = 640634676.

The previous prime is 640634639. The next prime is 640634699. The reversal of 640634677 is 776436046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 639786436 + 848241 = 25294^2 + 921^2 .

It is a cyclic number.

It is not a de Polignac number, because 640634677 - 2¹⁹ = 640110389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640634977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320317338 + 320317339.

It is an arithmetic number, because the mean of its divisors is an integer number (320317339).

Almost surely, 2^640634677 is an apocalyptic number.

It is an amenable number.

640634677 is a deficient number, since it is larger than the sum of its proper divisors (1).

640634677 is an equidigital number, since it uses as much as digits as its factorization.

640634677 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 508032, while the sum is 43.

The square root of 640634677 is about 25310.7620786100. The cubic root of 640634677 is about 862.0586506785.

The spelling of 640634677 in words is "six hundred forty million, six hundred thirty-four thousand, six hundred seventy-seven".