68001991 has 2 divisors, whose sum is σ = 68001992. Its totient is φ = 68001990.

The previous prime is 68001979. The next prime is 68002019. The reversal of 68001991 is 19910086.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 68001991 - 2⁵ = 68001959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (68001911) 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 as a sum of consecutive naturals, namely, 34000995 + 34000996.

It is an arithmetic number, because the mean of its divisors is an integer number (34000996).

Almost surely, 2^68001991 is an apocalyptic number.

68001991 is a deficient number, since it is larger than the sum of its proper divisors (1).

68001991 is an equidigital number, since it uses as much as digits as its factorization.

68001991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 34.

The square root of 68001991 is about 8246.3319724590. The cubic root of 68001991 is about 408.1694937682.

The spelling of 68001991 in words is "sixty-eight million, one thousand, nine hundred ninety-one".