68108991 has 4 divisors (see below), whose sum is σ = 90811992. Its totient is φ = 45405992.

The previous prime is 68108983. The next prime is 68108993. The reversal of 68108991 is 19980186.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 68108991 - 2³ = 68108983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68108993) 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, 11351496 + ... + 11351501.

It is an arithmetic number, because the mean of its divisors is an integer number (22702998).

Almost surely, 2^68108991 is an apocalyptic number.

68108991 is a deficient number, since it is larger than the sum of its proper divisors (22703001).

68108991 is a wasteful number, since it uses less digits than its factorization.

68108991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22703000.

The product of its (nonzero) digits is 31104, while the sum is 42.

The square root of 68108991 is about 8252.8171553719. The cubic root of 68108991 is about 408.3834642140.

The spelling of 68108991 in words is "sixty-eight million, one hundred eight thousand, nine hundred ninety-one".