640065536 has 56 divisors (see below), whose sum is σ = 1396617984. Its totient is φ = 290897920.

The previous prime is 640065511. The next prime is 640065563. The reversal of 640065536 is 635560046.

It is a junction number, because it is equal to n+sod(n) for n = 640065496 and 640065505.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86561 + ... + 93663.

Almost surely, 2^640065536 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 640065536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (698308992).

640065536 is an abundant number, since it is smaller than the sum of its proper divisors (756552448).

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

640065536 is an equidigital number, since it uses as much as digits as its factorization.

640065536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7140 (or 7116 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 35.

The square root of 640065536 is about 25299.5165171195. The cubic root of 640065536 is about 861.8032902237.

It can be divided in two parts, 6400 and 65536, that multiplied together give a square (419430400 = 20480²).

The spelling of 640065536 in words is "six hundred forty million, sixty-five thousand, five hundred thirty-six".