159491581 has 2 divisors, whose sum is σ = 159491582. Its totient is φ = 159491580.

The previous prime is 159491551. The next prime is 159491597. The reversal of 159491581 is 185194951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 108868356 + 50623225 = 10434^2 + 7115^2 .

It is an emirp because it is prime and its reverse (185194951) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 159491581 - 2¹⁵ = 159458813 is a prime.

It is a super-2 number, since 2×159491581² = 50875128819759122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (159491551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79745790 + 79745791.

It is an arithmetic number, because the mean of its divisors is an integer number (79745791).

Almost surely, 2^159491581 is an apocalyptic number.

It is an amenable number.

159491581 is a deficient number, since it is larger than the sum of its proper divisors (1).

159491581 is an equidigital number, since it uses as much as digits as its factorization.

159491581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64800, while the sum is 43.

The square root of 159491581 is about 12628.9976245148. The cubic root of 159491581 is about 542.3078875498.

The spelling of 159491581 in words is "one hundred fifty-nine million, four hundred ninety-one thousand, five hundred eighty-one".