688891791 has 16 divisors (see below), whose sum is σ = 1095381504. Its totient is φ = 376536864.

The previous prime is 688891757. The next prime is 688891807. The reversal of 688891791 is 197198886.

It is not a de Polignac number, because 688891791 - 2²² = 684697487 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688891711) 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 15 ways as a sum of consecutive naturals, for example, 712656 + ... + 713621.

It is an arithmetic number, because the mean of its divisors is an integer number (68461344).

Almost surely, 2^688891791 is an apocalyptic number.

688891791 is a deficient number, since it is larger than the sum of its proper divisors (406489713).

688891791 is a wasteful number, since it uses less digits than its factorization.

688891791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1426310.

The product of its digits is 1741824, while the sum is 57.

The square root of 688891791 is about 26246.7481985864. The cubic root of 688891791 is about 883.1822589941.

The spelling of 688891791 in words is "six hundred eighty-eight million, eight hundred ninety-one thousand, seven hundred ninety-one".