688619488561 has 3 divisors (see below), whose sum is σ = 688620318393. Its totient is φ = 688618658730.

The previous prime is 688619488517. The next prime is 688619488633. The reversal of 688619488561 is 165884916886.

The square root of 688619488561 is 829831.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 688619488561 - 2⁷ = 688619488433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (688619488961) 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 2 ways as a sum of consecutive naturals, for example, 414916 + ... + 1244746.

It is an arithmetic number, because the mean of its divisors is an integer number (229540106131).

Almost surely, 2^688619488561 is an apocalyptic number.

688619488561 is the 829831-st square number.

688619488561 is the 414916-th centered octagonal number.

It is an amenable number.

688619488561 is a deficient number, since it is larger than the sum of its proper divisors (829832).

688619488561 is an frugal number, since it uses more digits than its factorization.

688619488561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1659662 (or 829831 counting only the distinct ones).

The product of its digits is 159252480, while the sum is 70.

The spelling of 688619488561 in words is "six hundred eighty-eight billion, six hundred nineteen million, four hundred eighty-eight thousand, five hundred sixty-one".