161579861 has 2 divisors, whose sum is σ = 161579862. Its totient is φ = 161579860.

The previous prime is 161579837. The next prime is 161579863. The reversal of 161579861 is 168975161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 161137636 + 442225 = 12694^2 + 665^2 .

It is a cyclic number.

It is not a de Polignac number, because 161579861 - 2²⁶ = 94470997 is a prime.

It is a super-2 number, since 2×161579861² = 52216102961558642, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 161579863, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161579863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80789930 + 80789931.

It is an arithmetic number, because the mean of its divisors is an integer number (80789931).

Almost surely, 2^161579861 is an apocalyptic number.

It is an amenable number.

161579861 is a deficient number, since it is larger than the sum of its proper divisors (1).

161579861 is an equidigital number, since it uses as much as digits as its factorization.

161579861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 44.

The square root of 161579861 is about 12711.4067278173. The cubic root of 161579861 is about 544.6645086117.

The spelling of 161579861 in words is "one hundred sixty-one million, five hundred seventy-nine thousand, eight hundred sixty-one".