640784640 has 72 divisors (see below), whose sum is σ = 2046518208. Its totient is φ = 170874880.

The previous prime is 640784629. The next prime is 640784647. The reversal of 640784640 is 46487046.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (640784647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79596 + ... + 87275.

It is an arithmetic number, because the mean of its divisors is an integer number (28423864).

Almost surely, 2^640784640 is an apocalyptic number.

640784640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640784640 is an abundant number, since it is smaller than the sum of its proper divisors (1405733568).

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

640784640 is a wasteful number, since it uses less digits than its factorization.

640784640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166895 (or 166881 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 39.

The square root of 640784640 is about 25313.7243407603. The cubic root of 640784640 is about 862.1259104445.

The spelling of 640784640 in words is "six hundred forty million, seven hundred eighty-four thousand, six hundred forty".