680561945521 has 8 divisors (see below), whose sum is σ = 693459258440. Its totient is φ = 667761242112.

The previous prime is 680561945513. The next prime is 680561945549. The reversal of 680561945521 is 125549165086.

It can be written as a sum of positive squares in 4 ways, for example, as 3009071025 + 677552874496 = 54855^2 + 823136^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 680561945521 - 2³ = 680561945513 is a prime.

It is a super-2 number, since 2×680561945521² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (680561945221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24138156 + ... + 24166333.

It is an arithmetic number, because the mean of its divisors is an integer number (86682407305).

Almost surely, 2^680561945521 is an apocalyptic number.

It is an amenable number.

680561945521 is a deficient number, since it is larger than the sum of its proper divisors (12897312919).

680561945521 is a wasteful number, since it uses less digits than its factorization.

680561945521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48304755.

The product of its (nonzero) digits is 2592000, while the sum is 52.

The spelling of 680561945521 in words is "six hundred eighty billion, five hundred sixty-one million, nine hundred forty-five thousand, five hundred twenty-one".