1640904 has 16 divisors (see below), whose sum is σ = 4102320. Its totient is φ = 546960.

The previous prime is 1640887. The next prime is 1640927. The reversal of 1640904 is 4090461.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 68371 = 1640904 / (1 + 6 + 4 + 0 + 9 + 0 + 4).

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, 34162 + ... + 34209.

It is an arithmetic number, because the mean of its divisors is an integer number (256395).

2^1640904 is an apocalyptic number.

It is an amenable number.

1640904 is an abundant number, since it is smaller than the sum of its proper divisors (2461416).

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

1640904 is a wasteful number, since it uses less digits than its factorization.

1640904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68380 (or 68376 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 1640904 is about 1280.9777515632. The cubic root of 1640904 is about 117.9490347753.

The spelling of 1640904 in words is "one million, six hundred forty thousand, nine hundred four".