640425838 has 24 divisors (see below), whose sum is σ = 1073791296. Its totient is φ = 286041600.

The previous prime is 640425791. The next prime is 640425839. The reversal of 640425838 is 838524046.

It is a self number, because there is not a number n which added to its sum of digits gives 640425838.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640425839) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20083 + ... + 41038.

It is an arithmetic number, because the mean of its divisors is an integer number (44741304).

Almost surely, 2^640425838 is an apocalyptic number.

640425838 is a deficient number, since it is larger than the sum of its proper divisors (433365458).

640425838 is a wasteful number, since it uses less digits than its factorization.

640425838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61180 (or 61167 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 40.

The square root of 640425838 is about 25306.6362442740. The cubic root of 640425838 is about 861.9649670034.

The spelling of 640425838 in words is "six hundred forty million, four hundred twenty-five thousand, eight hundred thirty-eight".