181688712981 has 4 divisors (see below), whose sum is σ = 242251617312. Its totient is φ = 121125808652.

The previous prime is 181688712937. The next prime is 181688712983. The reversal of 181688712981 is 189217886181.

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 a cyclic number.

It is not a de Polignac number, because 181688712981 - 2⁶ = 181688712917 is a prime.

It is a super-2 number, since 2×181688712981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181688712983) 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 3 ways as a sum of consecutive naturals, for example, 30281452161 + ... + 30281452166.

It is an arithmetic number, because the mean of its divisors is an integer number (60562904328).

Almost surely, 2^181688712981 is an apocalyptic number.

It is an amenable number.

181688712981 is a deficient number, since it is larger than the sum of its proper divisors (60562904331).

181688712981 is an equidigital number, since it uses as much as digits as its factorization.

181688712981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60562904330.

The product of its digits is 3096576, while the sum is 60.

The spelling of 181688712981 in words is "one hundred eighty-one billion, six hundred eighty-eight million, seven hundred twelve thousand, nine hundred eighty-one".