1991113920 has 112 divisors (see below), whose sum is σ = 7024237920. Its totient is φ = 530961408.

The previous prime is 1991113919. The next prime is 1991113937. The reversal of 1991113920 is 293111991.

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 15 ways as a sum of consecutive naturals, for example, 106587 + ... + 123866.

It is an arithmetic number, because the mean of its divisors is an integer number (62716410).

Almost surely, 2^1991113920 is an apocalyptic number.

1991113920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1991113920 is an abundant number, since it is smaller than the sum of its proper divisors (5033124000).

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

1991113920 is a wasteful number, since it uses less digits than its factorization.

1991113920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230479 (or 230463 counting only the distinct ones).

The product of its (nonzero) digits is 4374, while the sum is 36.

The square root of 1991113920 is about 44621.8995561596. The cubic root of 1991113920 is about 1258.0523196680.

The spelling of 1991113920 in words is "one billion, nine hundred ninety-one million, one hundred thirteen thousand, nine hundred twenty".