681989161 has 4 divisors (see below), whose sum is σ = 779416192. Its totient is φ = 584562132.

The previous prime is 681989093. The next prime is 681989167. The reversal of 681989161 is 161989186.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 681989161 - 2²⁵ = 648434729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681989167) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48713505 + ... + 48713518.

It is an arithmetic number, because the mean of its divisors is an integer number (194854048).

Almost surely, 2^681989161 is an apocalyptic number.

It is an amenable number.

681989161 is a deficient number, since it is larger than the sum of its proper divisors (97427031).

681989161 is an equidigital number, since it uses as much as digits as its factorization.

681989161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97427030.

The product of its digits is 186624, while the sum is 49.

The square root of 681989161 is about 26114.9221901962. The cubic root of 681989161 is about 880.2225508922. Note that the first 3 decimals are identical.

The spelling of 681989161 in words is "six hundred eighty-one million, nine hundred eighty-nine thousand, one hundred sixty-one".