68109891 has 4 divisors (see below), whose sum is σ = 90813192. Its totient is φ = 45406592.

The previous prime is 68109863. The next prime is 68109907. The reversal of 68109891 is 19890186.

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 68109891 - 2⁶ = 68109827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (68109791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11351646 + ... + 11351651.

It is an arithmetic number, because the mean of its divisors is an integer number (22703298).

Almost surely, 2^68109891 is an apocalyptic number.

68109891 is a deficient number, since it is larger than the sum of its proper divisors (22703301).

68109891 is a wasteful number, since it uses less digits than its factorization.

68109891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22703300.

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

The square root of 68109891 is about 8252.8716820268. The cubic root of 68109891 is about 408.3852630147.

The spelling of 68109891 in words is "sixty-eight million, one hundred nine thousand, eight hundred ninety-one".