640866938 has 8 divisors (see below), whose sum is σ = 962188032. Its totient is φ = 320137596.

The previous prime is 640866907. The next prime is 640866943. The reversal of 640866938 is 839668046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145220 + ... + 149567.

It is an arithmetic number, because the mean of its divisors is an integer number (120273504).

Almost surely, 2^640866938 is an apocalyptic number.

640866938 is a deficient number, since it is larger than the sum of its proper divisors (321321094).

640866938 is a wasteful number, since it uses less digits than its factorization.

640866938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295876.

The product of its (nonzero) digits is 1492992, while the sum is 50.

The square root of 640866938 is about 25315.3498494490. The cubic root of 640866938 is about 862.1628173846.

The spelling of 640866938 in words is "six hundred forty million, eight hundred sixty-six thousand, nine hundred thirty-eight".