991920 has 40 divisors (see below), whose sum is σ = 3075696. Its totient is φ = 264448.

The previous prime is 991909. The next prime is 991927. The reversal of 991920 is 29199.

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

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991920.

It is not an unprimeable number, because it can be changed into a prime (991927) by changing a digit.

991920 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1827 + ... + 2306.

2⁹⁹¹⁹²⁰ is an apocalyptic number.

It is an amenable number.

991920 is an abundant number, since it is smaller than the sum of its proper divisors (2083776).

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

991920 is a wasteful number, since it uses less digits than its factorization.

991920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4149 (or 4143 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 30.

The square root of 991920 is about 995.9518060629. The cubic root of 991920 is about 99.7299379883.

The spelling of 991920 in words is "nine hundred ninety-one thousand, nine hundred twenty".