161145991 has 2 divisors, whose sum is σ = 161145992. Its totient is φ = 161145990.

The previous prime is 161145961. The next prime is 161146001. The reversal of 161145991 is 199541161.

161145991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 161145991 - 2⁷ = 161145863 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161145991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161145961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80572995 + 80572996.

It is an arithmetic number, because the mean of its divisors is an integer number (80572996).

Almost surely, 2^161145991 is an apocalyptic number.

161145991 is a deficient number, since it is larger than the sum of its proper divisors (1).

161145991 is an equidigital number, since it uses as much as digits as its factorization.

161145991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9720, while the sum is 37.

The square root of 161145991 is about 12694.3290882189. The cubic root of 161145991 is about 544.1765653344.

The spelling of 161145991 in words is "one hundred sixty-one million, one hundred forty-five thousand, nine hundred ninety-one".