181951825621 has 2 divisors, whose sum is σ = 181951825622. Its totient is φ = 181951825620.

The previous prime is 181951825613. The next prime is 181951825651. The reversal of 181951825621 is 126528159181.

181951825621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 150843684996 + 31108140625 = 388386^2 + 176375^2 .

It is a cyclic number.

It is not a de Polignac number, because 181951825621 - 2³ = 181951825613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181951825651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90975912810 + 90975912811.

It is an arithmetic number, because the mean of its divisors is an integer number (90975912811).

Almost surely, 2^181951825621 is an apocalyptic number.

It is an amenable number.

181951825621 is a deficient number, since it is larger than the sum of its proper divisors (1).

181951825621 is an equidigital number, since it uses as much as digits as its factorization.

181951825621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 345600, while the sum is 49.

The spelling of 181951825621 in words is "one hundred eighty-one billion, nine hundred fifty-one million, eight hundred twenty-five thousand, six hundred twenty-one".