68403991891 has 2 divisors, whose sum is σ = 68403991892. Its totient is φ = 68403991890.

The previous prime is 68403991879. The next prime is 68403991949. The reversal of 68403991891 is 19819930486.

It is an a-pointer prime, because the next prime (68403991949) can be obtained adding 68403991891 to its sum of digits (58).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 68403991891 - 2⁹ = 68403991379 is a prime.

It is a super-2 number, since 2×68403991891² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (68403991091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34201995945 + 34201995946.

It is an arithmetic number, because the mean of its divisors is an integer number (34201995946).

Almost surely, 2^68403991891 is an apocalyptic number.

68403991891 is a deficient number, since it is larger than the sum of its proper divisors (1).

68403991891 is an equidigital number, since it uses as much as digits as its factorization.

68403991891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3359232, while the sum is 58.

The spelling of 68403991891 in words is "sixty-eight billion, four hundred three million, nine hundred ninety-one thousand, eight hundred ninety-one".