688818888821 has 4 divisors (see below), whose sum is σ = 787221587232. Its totient is φ = 590416190412.

The previous prime is 688818888809. The next prime is 688818888859. The reversal of 688818888821 is 128888818886.

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 not a de Polignac number, because 688818888821 - 2¹⁸ = 688818626677 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 (688818888871) 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, 49201349195 + ... + 49201349208.

It is an arithmetic number, because the mean of its divisors is an integer number (196805396808).

Almost surely, 2^688818888821 is an apocalyptic number.

It is an amenable number.

688818888821 is a deficient number, since it is larger than the sum of its proper divisors (98402698411).

688818888821 is an equidigital number, since it uses as much as digits as its factorization.

688818888821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98402698410.

The product of its digits is 201326592, while the sum is 74.

The spelling of 688818888821 in words is "six hundred eighty-eight billion, eight hundred eighteen million, eight hundred eighty-eight thousand, eight hundred twenty-one".