640659456 has 130 divisors (see below), whose sum is σ = 1914826452. Its totient is φ = 213442560.

The previous prime is 640659421. The next prime is 640659473. The reversal of 640659456 is 654956046.

640659456 is a `hidden beast` number, since 6 + 4 + 0 + 6 + 594 + 56 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 330811 + ... + 332741.

Almost surely, 2^640659456 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 640659456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (957413226).

640659456 is an abundant number, since it is smaller than the sum of its proper divisors (1274166996).

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

640659456 is an equidigital number, since it uses as much as digits as its factorization.

640659456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1967 (or 1936 counting only the distinct ones).

The product of its (nonzero) digits is 777600, while the sum is 45.

The square root of 640659456 is about 25311.2515692132. The cubic root of 640659456 is about 862.0697650086.

The spelling of 640659456 in words is "six hundred forty million, six hundred fifty-nine thousand, four hundred fifty-six".