161918231 has 2 divisors, whose sum is σ = 161918232. Its totient is φ = 161918230.

The previous prime is 161918221. The next prime is 161918261. The reversal of 161918231 is 132819161.

It is a weak prime.

It is an emirp because it is prime and its reverse (132819161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161918231 - 2¹⁸ = 161656087 is a prime.

It is a super-2 number, since 2×161918231² = 52435027060338722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161918221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80959115 + 80959116.

It is an arithmetic number, because the mean of its divisors is an integer number (80959116).

Almost surely, 2^161918231 is an apocalyptic number.

161918231 is a deficient number, since it is larger than the sum of its proper divisors (1).

161918231 is an equidigital number, since it uses as much as digits as its factorization.

161918231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 32.

The square root of 161918231 is about 12724.7094662314. The cubic root of 161918231 is about 545.0444438127.

The spelling of 161918231 in words is "one hundred sixty-one million, nine hundred eighteen thousand, two hundred thirty-one".