165343891 has 2 divisors, whose sum is σ = 165343892. Its totient is φ = 165343890.

The previous prime is 165343889. The next prime is 165343903. The reversal of 165343891 is 198343561.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 165343891 - 2¹ = 165343889 is a prime.

Together with 165343889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (165343831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82671945 + 82671946.

It is an arithmetic number, because the mean of its divisors is an integer number (82671946).

Almost surely, 2^165343891 is an apocalyptic number.

165343891 is the 8133-rd centered pentagonal number.

165343891 is a deficient number, since it is larger than the sum of its proper divisors (1).

165343891 is an equidigital number, since it uses as much as digits as its factorization.

165343891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 40.

The square root of 165343891 is about 12858.6115502413. The cubic root of 165343891 is about 548.8614364036.

The spelling of 165343891 in words is "one hundred sixty-five million, three hundred forty-three thousand, eight hundred ninety-one".