640665360 has 120 divisors (see below), whose sum is σ = 2209810200. Its totient is φ = 166219776.

The previous prime is 640665331. The next prime is 640665373. The reversal of 640665360 is 63566046.

640665360 is a `hidden beast` number, since 64 + 0 + 66 + 536 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 172029456 + 468635904 = 13116^2 + 21648^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-3 number, since 3×640665360³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 14616 + ... + 38664.

It is an arithmetic number, because the mean of its divisors is an integer number (18415085).

Almost surely, 2^640665360 is an apocalyptic number.

640665360 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640665360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1104905100).

640665360 is an abundant number, since it is smaller than the sum of its proper divisors (1569144840).

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

640665360 is a wasteful number, since it uses less digits than its factorization.

640665360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24105 (or 24096 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 36.

The square root of 640665360 is about 25311.3681969189. The cubic root of 640665360 is about 862.0724131364.

The spelling of 640665360 in words is "six hundred forty million, six hundred sixty-five thousand, three hundred sixty".