640889088 has 144 divisors (see below), whose sum is σ = 1971070080. Its totient is φ = 181075968.

The previous prime is 640889059. The next prime is 640889113. The reversal of 640889088 is 880988046.

It is a self number, because there is not a number n which added to its sum of digits gives 640889088.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 520858 + ... + 522086.

Almost surely, 2^640889088 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640889088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (985535040).

640889088 is an abundant number, since it is smaller than the sum of its proper divisors (1330180992).

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

640889088 is a wasteful number, since it uses less digits than its factorization.

640889088 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1352 (or 1338 counting only the distinct ones).

The product of its (nonzero) digits is 884736, while the sum is 51.

The square root of 640889088 is about 25315.7873272786. The cubic root of 640889088 is about 862.1727501206.

The spelling of 640889088 in words is "six hundred forty million, eight hundred eighty-nine thousand, eighty-eight".