68287991 has 4 divisors (see below), whose sum is σ = 68419584. Its totient is φ = 68156400.

The previous prime is 68287981. The next prime is 68287993. The reversal of 68287991 is 19978286.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 68287991 - 2⁶ = 68287927 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 (68287993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65015 + ... + 66056.

It is an arithmetic number, because the mean of its divisors is an integer number (17104896).

Almost surely, 2^68287991 is an apocalyptic number.

68287991 is a deficient number, since it is larger than the sum of its proper divisors (131593).

68287991 is a wasteful number, since it uses less digits than its factorization.

68287991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131592.

The product of its digits is 435456, while the sum is 50.

The square root of 68287991 is about 8263.6548209615. The cubic root of 68287991 is about 408.7409142989.

The spelling of 68287991 in words is "sixty-eight million, two hundred eighty-seven thousand, nine hundred ninety-one".