181531680156 has 36 divisors (see below), whose sum is σ = 458926499304. Its totient is φ = 60503340000.

The previous prime is 181531680139. The next prime is 181531680203. The reversal of 181531680156 is 651086135181.

It is a happy number.

181531680156 is a `hidden beast` number, since 1 + 8 + 1 + 531 + 68 + 0 + 1 + 56 = 666.

181531680156 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9451 + ... + 602621.

It is an arithmetic number, because the mean of its divisors is an integer number (12747958314).

Almost surely, 2^181531680156 is an apocalyptic number.

It is an amenable number.

181531680156 is an abundant number, since it is smaller than the sum of its proper divisors (277394819148).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

181531680156 is a wasteful number, since it uses less digits than its factorization.

181531680156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601682 (or 601677 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 45.

The spelling of 181531680156 in words is "one hundred eighty-one billion, five hundred thirty-one million, six hundred eighty thousand, one hundred fifty-six".