181005521 has 2 divisors, whose sum is σ = 181005522. Its totient is φ = 181005520.

The previous prime is 181005491. The next prime is 181005523. The reversal of 181005521 is 125500181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155351296 + 25654225 = 12464^2 + 5065^2 .

It is a cyclic number.

It is not a de Polignac number, because 181005521 - 2¹⁰ = 181004497 is a prime.

It is a Sophie Germain prime.

Together with 181005523, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (181005523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90502760 + 90502761.

It is an arithmetic number, because the mean of its divisors is an integer number (90502761).

Almost surely, 2^181005521 is an apocalyptic number.

It is an amenable number.

181005521 is a deficient number, since it is larger than the sum of its proper divisors (1).

181005521 is an equidigital number, since it uses as much as digits as its factorization.

181005521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 400, while the sum is 23.

The square root of 181005521 is about 13453.8292318581. The cubic root of 181005521 is about 565.6710339751.

The spelling of 181005521 in words is "one hundred eighty-one million, five thousand, five hundred twenty-one".