640885139 has 2 divisors, whose sum is σ = 640885140. Its totient is φ = 640885138.

The previous prime is 640885129. The next prime is 640885153. The reversal of 640885139 is 931588046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640885139 - 2¹⁶ = 640819603 is a prime.

It is a super-2 number, since 2×640885139² = 821467522782098642, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640885139.

It is not a weakly prime, because it can be changed into another prime (640885129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320442569 + 320442570.

It is an arithmetic number, because the mean of its divisors is an integer number (320442570).

Almost surely, 2^640885139 is an apocalyptic number.

640885139 is a deficient number, since it is larger than the sum of its proper divisors (1).

640885139 is an equidigital number, since it uses as much as digits as its factorization.

640885139 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 207360, while the sum is 44.

The square root of 640885139 is about 25315.7093323494. The cubic root of 640885139 is about 862.1709792853.

The spelling of 640885139 in words is "six hundred forty million, eight hundred eighty-five thousand, one hundred thirty-nine".