68401991 has 12 divisors (see below), whose sum is σ = 80348112. Its totient is φ = 58056768.

The previous prime is 68401987. The next prime is 68402029. The reversal of 68401991 is 19910486.

It is a happy number.

It is not a de Polignac number, because 68401991 - 2² = 68401987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68401961) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1730 + ... + 11823.

It is an arithmetic number, because the mean of its divisors is an integer number (6695676).

Almost surely, 2^68401991 is an apocalyptic number.

68401991 is a deficient number, since it is larger than the sum of its proper divisors (11946121).

68401991 is a wasteful number, since it uses less digits than its factorization.

68401991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13670 (or 13663 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 68401991 is about 8270.5496189794. The cubic root of 68401991 is about 408.9682385970.

The spelling of 68401991 in words is "sixty-eight million, four hundred one thousand, nine hundred ninety-one".