640322879 has 4 divisors (see below), whose sum is σ = 731797584. Its totient is φ = 548848176.

The previous prime is 640322873. The next prime is 640322909. The reversal of 640322879 is 978223046.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 978223046 = 2 ⋅489111523.

It is a cyclic number.

It is not a de Polignac number, because 640322879 - 2⁸ = 640322623 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640322873) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45737342 + ... + 45737355.

It is an arithmetic number, because the mean of its divisors is an integer number (182949396).

Almost surely, 2^640322879 is an apocalyptic number.

640322879 is a deficient number, since it is larger than the sum of its proper divisors (91474705).

640322879 is an equidigital number, since it uses as much as digits as its factorization.

640322879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91474704.

The product of its (nonzero) digits is 145152, while the sum is 41.

The square root of 640322879 is about 25304.6019332453. The cubic root of 640322879 is about 861.9187728401.

The spelling of 640322879 in words is "six hundred forty million, three hundred twenty-two thousand, eight hundred seventy-nine".