68899991 has 2 divisors, whose sum is σ = 68899992. Its totient is φ = 68899990.

The previous prime is 68899931. The next prime is 68899993. The reversal of 68899991 is 19999886.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 68899991 - 2²² = 64705687 is a prime.

Together with 68899993, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 68899991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (68899993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34449995 + 34449996.

It is an arithmetic number, because the mean of its divisors is an integer number (34449996).

Almost surely, 2^68899991 is an apocalyptic number.

68899991 is a deficient number, since it is larger than the sum of its proper divisors (1).

68899991 is an equidigital number, since it uses as much as digits as its factorization.

68899991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2519424, while the sum is 59.

The square root of 68899991 is about 8300.6018456495. The cubic root of 68899991 is about 409.9583360399.

The spelling of 68899991 in words is "sixty-eight million, eight hundred ninety-nine thousand, nine hundred ninety-one".