181863658661 has 2 divisors, whose sum is σ = 181863658662. Its totient is φ = 181863658660.

The previous prime is 181863658619. The next prime is 181863658783. The reversal of 181863658661 is 166856368181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165043125025 + 16820533636 = 406255^2 + 129694^2 .

It is an emirp because it is prime and its reverse (166856368181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181863658661 - 2⁶ = 181863658597 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 181863658661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181863688661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90931829330 + 90931829331.

It is an arithmetic number, because the mean of its divisors is an integer number (90931829331).

Almost surely, 2^181863658661 is an apocalyptic number.

It is an amenable number.

181863658661 is a deficient number, since it is larger than the sum of its proper divisors (1).

181863658661 is an equidigital number, since it uses as much as digits as its factorization.

181863658661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9953280, while the sum is 59.

The spelling of 181863658661 in words is "one hundred eighty-one billion, eight hundred sixty-three million, six hundred fifty-eight thousand, six hundred sixty-one".