181162561 has 2 divisors, whose sum is σ = 181162562. Its totient is φ = 181162560.

The previous prime is 181162547. The next prime is 181162603. The reversal of 181162561 is 165261181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162715536 + 18447025 = 12756^2 + 4295^2 .

It is a cyclic number.

It is not a de Polignac number, because 181162561 - 2⁹ = 181162049 is a prime.

It is not a weakly prime, because it can be changed into another prime (181163561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90581280 + 90581281.

It is an arithmetic number, because the mean of its divisors is an integer number (90581281).

Almost surely, 2^181162561 is an apocalyptic number.

It is an amenable number.

181162561 is a deficient number, since it is larger than the sum of its proper divisors (1).

181162561 is an equidigital number, since it uses as much as digits as its factorization.

181162561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 31.

The square root of 181162561 is about 13459.6642231521. The cubic root of 181162561 is about 565.8345783440.

The spelling of 181162561 in words is "one hundred eighty-one million, one hundred sixty-two thousand, five hundred sixty-one".