180081991 has 2 divisors, whose sum is σ = 180081992. Its totient is φ = 180081990.

The previous prime is 180081971. The next prime is 180082009. The reversal of 180081991 is 199180081.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (199180081) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 166180081 and 180081661.

It is a cyclic number.

It is not a de Polignac number, because 180081991 - 2²¹ = 177984839 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 180081991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (180081961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90040995 + 90040996.

It is an arithmetic number, because the mean of its divisors is an integer number (90040996).

Almost surely, 2^180081991 is an apocalyptic number.

180081991 is a deficient number, since it is larger than the sum of its proper divisors (1).

180081991 is an equidigital number, since it uses as much as digits as its factorization.

180081991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 37.

The square root of 180081991 is about 13419.4631412736. The cubic root of 180081991 is about 564.7073337430.

The spelling of 180081991 in words is "one hundred eighty million, eighty-one thousand, nine hundred ninety-one".