181965521 has 2 divisors, whose sum is σ = 181965522. Its totient is φ = 181965520.

The previous prime is 181965491. The next prime is 181965523. The reversal of 181965521 is 125569181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114725521 + 67240000 = 10711^2 + 8200^2 .

It is a cyclic number.

It is not a de Polignac number, because 181965521 - 2⁶ = 181965457 is a prime.

It is a super-2 number, since 2×181965521² = 66222901665602882, which contains 22 as substring.

Together with 181965523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (181965523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90982760 + 90982761.

It is an arithmetic number, because the mean of its divisors is an integer number (90982761).

Almost surely, 2^181965521 is an apocalyptic number.

It is an amenable number.

181965521 is a deficient number, since it is larger than the sum of its proper divisors (1).

181965521 is an equidigital number, since it uses as much as digits as its factorization.

181965521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21600, while the sum is 38.

The square root of 181965521 is about 13489.4596259450. The cubic root of 181965521 is about 566.6693220560.

The spelling of 181965521 in words is "one hundred eighty-one million, nine hundred sixty-five thousand, five hundred twenty-one".