2117128991 has 8 divisors (see below), whose sum is σ = 2147255040. Its totient is φ = 2087033472.

The previous prime is 2117128987. The next prime is 2117129029. The reversal of 2117128991 is 1998217112.

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

It is a cyclic number.

It is not a de Polignac number, because 2117128991 - 2² = 2117128987 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 (2117128901) 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, 156971 + ... + 169923.

It is an arithmetic number, because the mean of its divisors is an integer number (268406880).

Almost surely, 2^2117128991 is an apocalyptic number.

2117128991 is a deficient number, since it is larger than the sum of its proper divisors (30126049).

2117128991 is a wasteful number, since it uses less digits than its factorization.

2117128991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15265.

The product of its digits is 18144, while the sum is 41.

The square root of 2117128991 is about 46012.2700048585. The cubic root of 2117128991 is about 1284.0514917983.

The spelling of 2117128991 in words is "two billion, one hundred seventeen million, one hundred twenty-eight thousand, nine hundred ninety-one".