640639702 has 4 divisors (see below), whose sum is σ = 960959556. Its totient is φ = 320319850.

The previous prime is 640639669. The next prime is 640639717. The reversal of 640639702 is 207936046.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160159924 + ... + 160159927.

It is an arithmetic number, because the mean of its divisors is an integer number (240239889).

Almost surely, 2^640639702 is an apocalyptic number.

640639702 is a deficient number, since it is larger than the sum of its proper divisors (320319854).

640639702 is a wasteful number, since it uses less digits than its factorization.

640639702 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320319853.

The product of its (nonzero) digits is 54432, while the sum is 37.

The square root of 640639702 is about 25310.8613444900. The cubic root of 640639702 is about 862.0609046065.

The spelling of 640639702 in words is "six hundred forty million, six hundred thirty-nine thousand, seven hundred two".