688994138879 has 4 divisors (see below), whose sum is σ = 689774427576. Its totient is φ = 688213850184.

The previous prime is 688994138867. The next prime is 688994138927. The reversal of 688994138879 is 978831499886.

688994138879 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 688994138879 - 2³⁶ = 620274662143 is a prime.

It is a super-2 number, since 2×688994138879² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688994138279) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 390143024 + ... + 390144789.

It is an arithmetic number, because the mean of its divisors is an integer number (172443606894).

Almost surely, 2^688994138879 is an apocalyptic number.

688994138879 is a deficient number, since it is larger than the sum of its proper divisors (780288697).

688994138879 is an equidigital number, since it uses as much as digits as its factorization.

688994138879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 780288696.

The product of its digits is 1504935936, while the sum is 80.

The spelling of 688994138879 in words is "six hundred eighty-eight billion, nine hundred ninety-four million, one hundred thirty-eight thousand, eight hundred seventy-nine".