913681721689 has 27 divisors (see below), whose sum is σ = 1014580348509. Its totient is φ = 822198558720.

The previous prime is 913681721671. The next prime is 913681721713. The reversal of 913681721689 is 986127186319.

The square root of 913681721689 is 955867.

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

It can be written as a sum of positive squares in 4 ways, for example, as 435382227225 + 478299494464 = 659835^2 + 691592^2 .

It is not a de Polignac number, because 913681721689 - 2¹¹ = 913681719641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (913681721089) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1188142297 + ... + 1188143065.

Almost surely, 2^913681721689 is an apocalyptic number.

913681721689 is the 955867-th square number.

913681721689 is the 477934-th centered octagonal number.

It is an amenable number.

913681721689 is a deficient number, since it is larger than the sum of its proper divisors (100898626820).

913681721689 is an frugal number, since it uses more digits than its factorization.

913681721689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1786 (or 893 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 61.

The spelling of 913681721689 in words is "nine hundred thirteen billion, six hundred eighty-one million, seven hundred twenty-one thousand, six hundred eighty-nine".