688420343521 has 9 divisors (see below), whose sum is σ = 726576613011. Its totient is φ = 652172759064.

The previous prime is 688420343503. The next prime is 688420343537. The reversal of 688420343521 is 125343024886.

The square root of 688420343521 is 829711.

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

It can be written as a sum of positive squares in only one way, i.e., 293860483921 + 394559859600 = 542089^2 + 628140^2 .

It is not a de Polignac number, because 688420343521 - 2⁷ = 688420343393 is a prime.

It is not an unprimeable number, because it can be changed into a prime (688420343551) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 15742675 + ... + 15786343.

It is an arithmetic number, because the mean of its divisors is an integer number (80730734779).

Almost surely, 2^688420343521 is an apocalyptic number.

688420343521 is the 829711-st square number.

688420343521 is the 414856-th centered octagonal number.

It is an amenable number.

688420343521 is a deficient number, since it is larger than the sum of its proper divisors (38156269490).

688420343521 is an frugal number, since it uses more digits than its factorization.

688420343521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87376 (or 43688 counting only the distinct ones).

The product of its (nonzero) digits is 1105920, while the sum is 46.

The spelling of 688420343521 in words is "six hundred eighty-eight billion, four hundred twenty million, three hundred forty-three thousand, five hundred twenty-one".