165561151101581 has 2 divisors, whose sum is σ = 165561151101582. Its totient is φ = 165561151101580.

The previous prime is 165561151101529. The next prime is 165561151101589. The reversal of 165561151101581 is 185101151165561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 162087680225956 + 3473470875625 = 12731366^2 + 1863725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165561151101581 is a prime.

It is a super-2 number, since 2×165561151101581² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165561151101589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82780575550790 + 82780575550791.

It is an arithmetic number, because the mean of its divisors is an integer number (82780575550791).

Almost surely, 2^{165561151101581} is an apocalyptic number.

It is an amenable number.

165561151101581 is a deficient number, since it is larger than the sum of its proper divisors (1).

165561151101581 is an equidigital number, since it uses as much as digits as its factorization.

165561151101581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 180000, while the sum is 47.

The spelling of 165561151101581 in words is "one hundred sixty-five trillion, five hundred sixty-one billion, one hundred fifty-one million, one hundred one thousand, five hundred eighty-one".