640993500 has 720 divisors, whose sum is σ = 2711348640. Its totient is φ = 130636800.

The previous prime is 640993487. The next prime is 640993537. The reversal of 640993500 is 5399046.

640993500 is a `hidden beast` number, since 64 + 0 + 9 + 93 + 500 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 33736491 + ... + 33736509.

It is an arithmetic number, because the mean of its divisors is an integer number (3765762).

Almost surely, 2^640993500 is an apocalyptic number.

640993500 is a gapful number since it is divisible by the number (60) 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 640993500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1355674320).

640993500 is an abundant number, since it is smaller than the sum of its proper divisors (2070355140).

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

640993500 is a wasteful number, since it uses less digits than its factorization.

640993500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 29160, while the sum is 36.

The square root of 640993500 is about 25317.8494347368. The cubic root of 640993500 is about 862.2195685663.

The spelling of 640993500 in words is "six hundred forty million, nine hundred ninety-three thousand, five hundred".