640557038 has 16 divisors (see below), whose sum is σ = 1093758336. Its totient is φ = 278502840.

The previous prime is 640557037. The next prime is 640557053. The reversal of 640557038 is 830755046.

It is a junction number, because it is equal to n+sod(n) for n = 640556992 and 640557010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640557037) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 632456 + ... + 633467.

It is an arithmetic number, because the mean of its divisors is an integer number (68359896).

Almost surely, 2^640557038 is an apocalyptic number.

640557038 is a deficient number, since it is larger than the sum of its proper divisors (453201298).

640557038 is a wasteful number, since it uses less digits than its factorization.

640557038 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1265959.

The product of its (nonzero) digits is 100800, while the sum is 38.

The square root of 640557038 is about 25309.2283169598. The cubic root of 640557038 is about 862.0238247588.

The spelling of 640557038 in words is "six hundred forty million, five hundred fifty-seven thousand, thirty-eight".