640668424 has 16 divisors (see below), whose sum is σ = 1310458320. Its totient is φ = 291212880.

The previous prime is 640668349. The next prime is 640668449. The reversal of 640668424 is 424866046.

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, 3640074 + ... + 3640249.

It is an arithmetic number, because the mean of its divisors is an integer number (81903645).

Almost surely, 2^640668424 is an apocalyptic number.

It is an amenable number.

640668424 is an abundant number, since it is smaller than the sum of its proper divisors (669789896).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640668424 is a wasteful number, since it uses less digits than its factorization.

640668424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7280340 (or 7280336 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 40.

The square root of 640668424 is about 25311.4287230097. The cubic root of 640668424 is about 862.0737874293.

The spelling of 640668424 in words is "six hundred forty million, six hundred sixty-eight thousand, four hundred twenty-four".