181901281 has 2 divisors, whose sum is σ = 181901282. Its totient is φ = 181901280.

The previous prime is 181901267. The next prime is 181901347. The reversal of 181901281 is 182109181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 170067681 + 11833600 = 13041^2 + 3440^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181901281 is a prime.

It is a super-2 number, since 2×181901281² = 66176152058881922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (181901221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90950640 + 90950641.

It is an arithmetic number, because the mean of its divisors is an integer number (90950641).

Almost surely, 2^181901281 is an apocalyptic number.

It is an amenable number.

181901281 is a deficient number, since it is larger than the sum of its proper divisors (1).

181901281 is an equidigital number, since it uses as much as digits as its factorization.

181901281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 31.

The square root of 181901281 is about 13487.0782973927. The cubic root of 181901281 is about 566.6026297110.

The spelling of 181901281 in words is "one hundred eighty-one million, nine hundred one thousand, two hundred eighty-one".