640826984 has 48 divisors (see below), whose sum is σ = 1449324000. Its totient is φ = 260177184.

The previous prime is 640826969. The next prime is 640827029. The reversal of 640826984 is 489628046.

It is a hoax number, since the sum of its digits (47) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4367 + ... + 36065.

It is an arithmetic number, because the mean of its divisors is an integer number (30194250).

Almost surely, 2^640826984 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 640826984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (724662000).

640826984 is an abundant number, since it is smaller than the sum of its proper divisors (808497016).

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

640826984 is a wasteful number, since it uses less digits than its factorization.

640826984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31750 (or 31727 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 47.

The square root of 640826984 is about 25314.5607111796. The cubic root of 640826984 is about 862.1449002128.

The spelling of 640826984 in words is "six hundred forty million, eight hundred twenty-six thousand, nine hundred eighty-four".