1991169 has 16 divisors (see below), whose sum is σ = 3052800. Its totient is φ = 1281168.

The previous prime is 1991153. The next prime is 1991177. The reversal of 1991169 is 9611991.

It is not a de Polignac number, because 1991169 - 2⁴ = 1991153 is a prime.

It is a super-2 number, since 2×1991169² = 7929507973122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1991189) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 489 + ... + 2054.

It is an arithmetic number, because the mean of its divisors is an integer number (190800).

2^1991169 is an apocalyptic number.

It is an amenable number.

1991169 is a deficient number, since it is larger than the sum of its proper divisors (1061631).

1991169 is a wasteful number, since it uses less digits than its factorization.

1991169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2581 (or 2575 counting only the distinct ones).

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

The square root of 1991169 is about 1411.0878781989. The cubic root of 1991169 is about 125.8063920023.

The spelling of 1991169 in words is "one million, nine hundred ninety-one thousand, one hundred sixty-nine".