640660361220 has 144 divisors (see below), whose sum is σ = 2231582633280. Its totient is φ = 147137299200.

The previous prime is 640660361219. The next prime is 640660361249. The reversal of 640660361220 is 22163066046.

640660361220 is a `hidden beast` number, since 6 + 40 + 6 + 603 + 6 + 1 + 2 + 2 + 0 = 666.

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 47 ways as a sum of consecutive naturals, for example, 8477271 + ... + 8552510.

It is an arithmetic number, because the mean of its divisors is an integer number (15497101620).

Almost surely, 2^640660361220 is an apocalyptic number.

640660361220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640660361220 is an abundant number, since it is smaller than the sum of its proper divisors (1590922272060).

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

640660361220 is a wasteful number, since it uses less digits than its factorization.

640660361220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17029826 (or 17029821 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The spelling of 640660361220 in words is "six hundred forty billion, six hundred sixty million, three hundred sixty-one thousand, two hundred twenty".