640686009600 has 648 divisors, whose sum is σ = 2819219475072. Its totient is φ = 135176601600.

The previous prime is 640686009571. The next prime is 640686009619. The reversal of 640686009600 is 6900686046.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 5180485 + ... + 5302715.

Almost surely, 2^640686009600 is an apocalyptic number.

640686009600 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 640686009600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1409609737536).

640686009600 is an abundant number, since it is smaller than the sum of its proper divisors (2178533465472).

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

640686009600 is a wasteful number, since it uses less digits than its factorization.

640686009600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122283 (or 122261 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The spelling of 640686009600 in words is "six hundred forty billion, six hundred eighty-six million, nine thousand, six hundred".