640609279 has 2 divisors, whose sum is σ = 640609280. Its totient is φ = 640609278.

The previous prime is 640609261. The next prime is 640609289. The reversal of 640609279 is 972906046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640609279 - 2⁹ = 640608767 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640609289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320304639 + 320304640.

It is an arithmetic number, because the mean of its divisors is an integer number (320304640).

Almost surely, 2^640609279 is an apocalyptic number.

640609279 is a deficient number, since it is larger than the sum of its proper divisors (1).

640609279 is an equidigital number, since it uses as much as digits as its factorization.

640609279 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 163296, while the sum is 43.

The square root of 640609279 is about 25310.2603503006. The cubic root of 640609279 is about 862.0472584057.

The spelling of 640609279 in words is "six hundred forty million, six hundred nine thousand, two hundred seventy-nine".