6688943857 has 4 divisors (see below), whose sum is σ = 6695009280. Its totient is φ = 6682878436.

The previous prime is 6688943843. The next prime is 6688943887. The reversal of 6688943857 is 7583498866.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6688943857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6688943887) 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, 3031057 + ... + 3033262.

It is an arithmetic number, because the mean of its divisors is an integer number (1673752320).

Almost surely, 2^6688943857 is an apocalyptic number.

It is an amenable number.

6688943857 is a deficient number, since it is larger than the sum of its proper divisors (6065423).

6688943857 is a wasteful number, since it uses less digits than its factorization.

6688943857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6065422.

The product of its digits is 69672960, while the sum is 64.

The square root of 6688943857 is about 81785.9636918218. The cubic root of 6688943857 is about 1884.1660909050.

The spelling of 6688943857 in words is "six billion, six hundred eighty-eight million, nine hundred forty-three thousand, eight hundred fifty-seven".