68187991 has 2 divisors, whose sum is σ = 68187992. Its totient is φ = 68187990.

The previous prime is 68187983. The next prime is 68188007. The reversal of 68187991 is 19978186.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 68187991 - 2³ = 68187983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (68185991) 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, 34093995 + 34093996.

It is an arithmetic number, because the mean of its divisors is an integer number (34093996).

Almost surely, 2^68187991 is an apocalyptic number.

68187991 is a deficient number, since it is larger than the sum of its proper divisors (1).

68187991 is an equidigital number, since it uses as much as digits as its factorization.

68187991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 49.

The square root of 68187991 is about 8257.6020126911. The cubic root of 68187991 is about 408.5412986276.

The spelling of 68187991 in words is "sixty-eight million, one hundred eighty-seven thousand, nine hundred ninety-one".