68891999991 has 4 divisors (see below), whose sum is σ = 91855999992. Its totient is φ = 45927999992.

The previous prime is 68891999959. The next prime is 68891999999. The reversal of 68891999991 is 19999919886.

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 68891999991 - 2⁵ = 68891999959 is a prime.

It is a super-2 number, since 2×68891999991² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68891999999) 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, 11481999996 + ... + 11482000001.

It is an arithmetic number, because the mean of its divisors is an integer number (22963999998).

Almost surely, 2^68891999991 is an apocalyptic number.

68891999991 is a deficient number, since it is larger than the sum of its proper divisors (22964000001).

68891999991 is a wasteful number, since it uses less digits than its factorization.

68891999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22964000000.

The product of its digits is 204073344, while the sum is 78.

The spelling of 68891999991 in words is "sixty-eight billion, eight hundred ninety-one million, nine hundred ninety-nine thousand, nine hundred ninety-one".