640533888 has 96 divisors (see below), whose sum is σ = 1951686360. Its totient is φ = 200945664.

The previous prime is 640533853. The next prime is 640533917. The reversal of 640533888 is 888335046.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

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, 3231 + ... + 35937.

Almost surely, 2^640533888 is an apocalyptic number.

640533888 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640533888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (975843180).

640533888 is an abundant number, since it is smaller than the sum of its proper divisors (1311152472).

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

640533888 is a wasteful number, since it uses less digits than its factorization.

640533888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32744 (or 32729 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 45.

The square root of 640533888 is about 25308.7709697646. The cubic root of 640533888 is about 862.0134399995.

The spelling of 640533888 in words is "six hundred forty million, five hundred thirty-three thousand, eight hundred eighty-eight".