640763784 has 96 divisors (see below), whose sum is σ = 1838229120. Its totient is φ = 209013696.

The previous prime is 640763759. The next prime is 640763791. The reversal of 640763784 is 487367046.

640763784 is a `hidden beast` number, since 6 + 4 + 0 + 7 + 637 + 8 + 4 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 87862 + ... + 94874.

It is an arithmetic number, because the mean of its divisors is an integer number (19148220).

Almost surely, 2^640763784 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 640763784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (919114560).

640763784 is an abundant number, since it is smaller than the sum of its proper divisors (1197465336).

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

640763784 is a wasteful number, since it uses less digits than its factorization.

640763784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7081 (or 7065 counting only the distinct ones).

The product of its (nonzero) digits is 677376, while the sum is 45.

The square root of 640763784 is about 25313.3123869635. The cubic root of 640763784 is about 862.1165569676.

The spelling of 640763784 in words is "six hundred forty million, seven hundred sixty-three thousand, seven hundred eighty-four".