165581281 has 2 divisors, whose sum is σ = 165581282. Its totient is φ = 165581280.

The previous prime is 165581239. The next prime is 165581303. The reversal of 165581281 is 182185561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147865600 + 17715681 = 12160^2 + 4209^2 .

It is an emirp because it is prime and its reverse (182185561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165581281 - 2⁹ = 165580769 is a prime.

It is a super-2 number, since 2×165581281² = 54834321235201922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 165581281.

It is not a weakly prime, because it can be changed into another prime (165581681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82790640 + 82790641.

It is an arithmetic number, because the mean of its divisors is an integer number (82790641).

Almost surely, 2^165581281 is an apocalyptic number.

It is an amenable number.

165581281 is a deficient number, since it is larger than the sum of its proper divisors (1).

165581281 is an equidigital number, since it uses as much as digits as its factorization.

165581281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19200, while the sum is 37.

The square root of 165581281 is about 12867.8390182657. The cubic root of 165581281 is about 549.1239839730.

The spelling of 165581281 in words is "one hundred sixty-five million, five hundred eighty-one thousand, two hundred eighty-one".