2117991 has 8 divisors (see below), whose sum is σ = 2900464. Its totient is φ = 1373760.

The previous prime is 2117977. The next prime is 2118007. The reversal of 2117991 is 1997112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2117991 - 2¹⁰ = 2116967 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2117971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9430 + ... + 9651.

It is an arithmetic number, because the mean of its divisors is an integer number (362558).

2^2117991 is an apocalyptic number.

2117991 is a deficient number, since it is larger than the sum of its proper divisors (782473).

2117991 is a wasteful number, since it uses less digits than its factorization.

2117991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19121.

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

The square root of 2117991 is about 1455.3319209033. The cubic root of 2117991 is about 128.4225739369.

The spelling of 2117991 in words is "two million, one hundred seventeen thousand, nine hundred ninety-one".