181959916321 has 2 divisors, whose sum is σ = 181959916322. Its totient is φ = 181959916320.

The previous prime is 181959916301. The next prime is 181959916343. The reversal of 181959916321 is 123619959181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 178835106321 + 3124810000 = 422889^2 + 55900^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181959916321 is a prime.

It is a super-2 number, since 2×181959916321² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (181959916301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90979958160 + 90979958161.

It is an arithmetic number, because the mean of its divisors is an integer number (90979958161).

Almost surely, 2^181959916321 is an apocalyptic number.

It is an amenable number.

181959916321 is a deficient number, since it is larger than the sum of its proper divisors (1).

181959916321 is an equidigital number, since it uses as much as digits as its factorization.

181959916321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1049760, while the sum is 55.

The spelling of 181959916321 in words is "one hundred eighty-one billion, nine hundred fifty-nine million, nine hundred sixteen thousand, three hundred twenty-one".