640642180 has 24 divisors (see below), whose sum is σ = 1348363800. Its totient is φ = 255682560.

The previous prime is 640642153. The next prime is 640642183. The reversal of 640642180 is 81246046.

It can be written as a sum of positive squares in 4 ways, for example, as 19236996 + 621405184 = 4386^2 + 24928^2 .

It is not an unprimeable number, because it can be changed into a prime (640642183) 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, 26691 + ... + 44650.

It is an arithmetic number, because the mean of its divisors is an integer number (56181825).

Almost surely, 2^640642180 is an apocalyptic number.

It is an amenable number.

640642180 is an abundant number, since it is smaller than the sum of its proper divisors (707721620).

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

640642180 is a wasteful number, since it uses less digits than its factorization.

640642180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71799 (or 71797 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 31.

The square root of 640642180 is about 25310.9102957598. The cubic root of 640642180 is about 862.0620160915.

The spelling of 640642180 in words is "six hundred forty million, six hundred forty-two thousand, one hundred eighty".