1991172 has 12 divisors (see below), whose sum is σ = 4646096. Its totient is φ = 663720.

The previous prime is 1991153. The next prime is 1991177. The reversal of 1991172 is 2711991.

It is a tau number, because it is divible by the number of its divisors (12).

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (1991177) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82954 + ... + 82977.

2^1991172 is an apocalyptic number.

1991172 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1991172 is an abundant number, since it is smaller than the sum of its proper divisors (2654924).

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

1991172 is a wasteful number, since it uses less digits than its factorization.

1991172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165938 (or 165936 counting only the distinct ones).

The product of its digits is 1134, while the sum is 30.

The square root of 1991172 is about 1411.0889412082. The cubic root of 1991172 is about 125.8064551844.

The spelling of 1991172 in words is "one million, nine hundred ninety-one thousand, one hundred seventy-two".