19891920 has 40 divisors (see below), whose sum is σ = 61665696. Its totient is φ = 5304448.

The previous prime is 19891913. The next prime is 19891933. The reversal of 19891920 is 2919891.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41202 + ... + 41681.

Almost surely, 2^19891920 is an apocalyptic number.

19891920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19891920 is an abundant number, since it is smaller than the sum of its proper divisors (41773776).

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

19891920 is a wasteful number, since it uses less digits than its factorization.

19891920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82899 (or 82893 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 39.

The square root of 19891920 is about 4460.0358742952. The cubic root of 19891920 is about 270.9519211376.

The spelling of 19891920 in words is "nineteen million, eight hundred ninety-one thousand, nine hundred twenty".