161556231673 has 2 divisors, whose sum is σ = 161556231674. Its totient is φ = 161556231672.

The previous prime is 161556231649. The next prime is 161556231691. The reversal of 161556231673 is 376132655161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152453545209 + 9102686464 = 390453^2 + 95408^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161556231673 is a prime.

It is a super-2 number, since 2×161556231673² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161556231623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80778115836 + 80778115837.

It is an arithmetic number, because the mean of its divisors is an integer number (80778115837).

Almost surely, 2^161556231673 is an apocalyptic number.

It is an amenable number.

161556231673 is a deficient number, since it is larger than the sum of its proper divisors (1).

161556231673 is an equidigital number, since it uses as much as digits as its factorization.

161556231673 is an evil number, because the sum of its binary digits is even.

The product of its digits is 680400, while the sum is 46.

The spelling of 161556231673 in words is "one hundred sixty-one billion, five hundred fifty-six million, two hundred thirty-one thousand, six hundred seventy-three".