1640904660 has 72 divisors (see below), whose sum is σ = 4981243176. Its totient is φ = 437237760.

The previous prime is 1640904649. The next prime is 1640904673. The reversal of 1640904660 is 664090461.

1640904660 is a `hidden beast` number, since 1 + 640 + 9 + 0 + 4 + 6 + 6 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 549527364 + 1091377296 = 23442^2 + 33036^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 307132 + ... + 312428.

It is an arithmetic number, because the mean of its divisors is an integer number (69183933).

Almost surely, 2^1640904660 is an apocalyptic number.

1640904660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1640904660 is an abundant number, since it is smaller than the sum of its proper divisors (3340338516).

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

1640904660 is a wasteful number, since it uses less digits than its factorization.

1640904660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7033 (or 7028 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 1640904660 is about 40508.0814159348. The cubic root of 1640904660 is about 1179.4905058901.

The spelling of 1640904660 in words is "one billion, six hundred forty million, nine hundred four thousand, six hundred sixty".