161387561 has 2 divisors, whose sum is σ = 161387562. Its totient is φ = 161387560.

The previous prime is 161387549. The next prime is 161387591. The reversal of 161387561 is 165783161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 125865961 + 35521600 = 11219^2 + 5960^2 .

It is an emirp because it is prime and its reverse (165783161) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161387561 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (161387591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80693780 + 80693781.

It is an arithmetic number, because the mean of its divisors is an integer number (80693781).

Almost surely, 2^161387561 is an apocalyptic number.

It is an amenable number.

161387561 is a deficient number, since it is larger than the sum of its proper divisors (1).

161387561 is an equidigital number, since it uses as much as digits as its factorization.

161387561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 38.

The square root of 161387561 is about 12703.8404035945. The cubic root of 161387561 is about 544.4483501486.

The spelling of 161387561 in words is "one hundred sixty-one million, three hundred eighty-seven thousand, five hundred sixty-one".