681739585209 has 20 divisors (see below), whose sum is σ = 1024648988176. Its totient is φ = 451704747096.

The previous prime is 681739585199. The next prime is 681739585223. The reversal of 681739585209 is 902585937186.

681739585209 is a `hidden beast` number, since 6 + 8 + 17 + 3 + 95 + 8 + 520 + 9 = 666.

It is not a de Polignac number, because 681739585209 - 2¹⁹ = 681739060921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681739585229) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 25804399 + ... + 25830804.

Almost surely, 2^681739585209 is an apocalyptic number.

It is an amenable number.

681739585209 is a deficient number, since it is larger than the sum of its proper divisors (342909402967).

681739585209 is a wasteful number, since it uses less digits than its factorization.

681739585209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51635378 (or 51635369 counting only the distinct ones).

The product of its (nonzero) digits is 32659200, while the sum is 63.

The spelling of 681739585209 in words is "six hundred eighty-one billion, seven hundred thirty-nine million, five hundred eighty-five thousand, two hundred nine".