181266721 has 2 divisors, whose sum is σ = 181266722. Its totient is φ = 181266720.

The previous prime is 181266599. The next prime is 181266727. The reversal of 181266721 is 127662181.

181266721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 133656721 + 47610000 = 11561^2 + 6900^2 .

It is a cyclic number.

It is not a de Polignac number, because 181266721 - 2¹¹ = 181264673 is a prime.

It is not a weakly prime, because it can be changed into another prime (181266727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90633360 + 90633361.

It is an arithmetic number, because the mean of its divisors is an integer number (90633361).

Almost surely, 2^181266721 is an apocalyptic number.

It is an amenable number.

181266721 is a deficient number, since it is larger than the sum of its proper divisors (1).

181266721 is an equidigital number, since it uses as much as digits as its factorization.

181266721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 34.

The square root of 181266721 is about 13463.5330058644. The cubic root of 181266721 is about 565.9430003740.

The spelling of 181266721 in words is "one hundred eighty-one million, two hundred sixty-six thousand, seven hundred twenty-one".