686476874521 has 9 divisors (see below), whose sum is σ = 688540309599. Its totient is φ = 684419612184.

The previous prime is 686476874507. The next prime is 686476874563. The reversal of 686476874521 is 125478674686.

The square root of 686476874521 is 828539.

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., 460056975625 + 226419898896 = 678275^2 + 475836^2 .

It is a de Polignac number, because none of the positive numbers 2^k-686476874521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686476874581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 328928940 + ... + 328931026.

Almost surely, 2^686476874521 is an apocalyptic number.

686476874521 is the 828539-th square number.

686476874521 is the 414270-th centered octagonal number.

It is an amenable number.

686476874521 is a deficient number, since it is larger than the sum of its proper divisors (2063435078).

686476874521 is an frugal number, since it uses more digits than its factorization.

686476874521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4968 (or 2484 counting only the distinct ones).

The product of its digits is 108380160, while the sum is 64.

Multiplying 686476874521 by its sum of digits (64), we get a square (43934519969344 = 6628312²).

The spelling of 686476874521 in words is "six hundred eighty-six billion, four hundred seventy-six million, eight hundred seventy-four thousand, five hundred twenty-one".