1991904 has 24 divisors (see below), whose sum is σ = 5229000. Its totient is φ = 663936.

The previous prime is 1991893. The next prime is 1991911. The reversal of 1991904 is 4091991.

It is a tau number, because it is divible by the number of its divisors (24).

It is a congruent number.

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, 10279 + ... + 10470.

It is an arithmetic number, because the mean of its divisors is an integer number (217875).

2^1991904 is an apocalyptic number.

It is an amenable number.

1991904 is an abundant number, since it is smaller than the sum of its proper divisors (3237096).

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

1991904 is a wasteful number, since it uses less digits than its factorization.

1991904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20762 (or 20754 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 1991904 is about 1411.3482915284. The cubic root of 1991904 is about 125.8218697313.

The spelling of 1991904 in words is "one million, nine hundred ninety-one thousand, nine hundred four".