640749528 has 80 divisors (see below), whose sum is σ = 1800117000. Its totient is φ = 212937984.

The previous prime is 640749523. The next prime is 640749569. The reversal of 640749528 is 825947046.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640749523) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 244288 + ... + 246896.

Almost surely, 2^640749528 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 640749528, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (900058500).

640749528 is an abundant number, since it is smaller than the sum of its proper divisors (1159367472).

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

640749528 is a wasteful number, since it uses less digits than its factorization.

640749528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3006 (or 2993 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The square root of 640749528 is about 25313.0307944347. The cubic root of 640749528 is about 862.1101633349.

The spelling of 640749528 in words is "six hundred forty million, seven hundred forty-nine thousand, five hundred twenty-eight".