640764744 has 64 divisors (see below), whose sum is σ = 1660608000. Its totient is φ = 205793280.

The previous prime is 640764713. The next prime is 640764767. The reversal of 640764744 is 447467046.

It is a junction number, because it is equal to n+sod(n) for n = 640764696 and 640764705.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 646089 + ... + 647079.

It is an arithmetic number, because the mean of its divisors is an integer number (25947000).

Almost surely, 2^640764744 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 640764744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (830304000).

640764744 is an abundant number, since it is smaller than the sum of its proper divisors (1019843256).

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

640764744 is a wasteful number, since it uses less digits than its factorization.

640764744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1958 (or 1954 counting only the distinct ones).

The product of its (nonzero) digits is 451584, while the sum is 42.

The square root of 640764744 is about 25313.3313493108. The cubic root of 640764744 is about 862.1169875118.

The spelling of 640764744 in words is "six hundred forty million, seven hundred sixty-four thousand, seven hundred forty-four".