108991591 has 4 divisors (see below), whose sum is σ = 110010312. Its totient is φ = 107972872.

The previous prime is 108991579. The next prime is 108991601. The reversal of 108991591 is 195199801.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 195199801 = 2269 ⋅86029.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-108991591 is a prime.

It is a super-2 number, since 2×108991591² = 23758333817422562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (108991501) 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, 509200 + ... + 509413.

It is an arithmetic number, because the mean of its divisors is an integer number (27502578).

Almost surely, 2^108991591 is an apocalyptic number.

108991591 is a deficient number, since it is larger than the sum of its proper divisors (1018721).

108991591 is a wasteful number, since it uses less digits than its factorization.

108991591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018720.

The product of its (nonzero) digits is 29160, while the sum is 43.

The square root of 108991591 is about 10439.9037830815. The cubic root of 108991591 is about 477.6733338171.

The spelling of 108991591 in words is "one hundred eight million, nine hundred ninety-one thousand, five hundred ninety-one".