161357881 has 2 divisors, whose sum is σ = 161357882. Its totient is φ = 161357880.

The previous prime is 161357879. The next prime is 161357923. The reversal of 161357881 is 188753161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 121352256 + 40005625 = 11016^2 + 6325^2 .

It is a cyclic number.

It is not a de Polignac number, because 161357881 - 2¹ = 161357879 is a prime.

It is a super-2 number, since 2×161357881² = 52072731521620322, which contains 22 as substring.

Together with 161357879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (161357831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80678940 + 80678941.

It is an arithmetic number, because the mean of its divisors is an integer number (80678941).

Almost surely, 2^161357881 is an apocalyptic number.

It is an amenable number.

161357881 is a deficient number, since it is larger than the sum of its proper divisors (1).

161357881 is an equidigital number, since it uses as much as digits as its factorization.

161357881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 40.

The square root of 161357881 is about 12702.6721991871. The cubic root of 161357881 is about 544.4149724880.

The spelling of 161357881 in words is "one hundred sixty-one million, three hundred fifty-seven thousand, eight hundred eighty-one".