161319581 has 2 divisors, whose sum is σ = 161319582. Its totient is φ = 161319580.

The previous prime is 161319551. The next prime is 161319589. The reversal of 161319581 is 185913161.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 93915481 + 67404100 = 9691^2 + 8210^2 .

It is a cyclic number.

It is not a de Polignac number, because 161319581 - 2⁶ = 161319517 is a prime.

It is a super-2 number, since 2×161319581² = 52048014428031122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161319589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80659790 + 80659791.

It is an arithmetic number, because the mean of its divisors is an integer number (80659791).

Almost surely, 2^161319581 is an apocalyptic number.

It is an amenable number.

161319581 is a deficient number, since it is larger than the sum of its proper divisors (1).

161319581 is an equidigital number, since it uses as much as digits as its factorization.

161319581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 35.

The square root of 161319581 is about 12701.1645529062. The cubic root of 161319581 is about 544.3718948619.

The spelling of 161319581 in words is "one hundred sixty-one million, three hundred nineteen thousand, five hundred eighty-one".