165863891 has 2 divisors, whose sum is σ = 165863892. Its totient is φ = 165863890.

The previous prime is 165863869. The next prime is 165863909. The reversal of 165863891 is 198368561.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 165863891 - 2²² = 161669587 is a prime.

It is a super-3 number, since 3×165863891³ (a number of 26 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (165863801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82931945 + 82931946.

It is an arithmetic number, because the mean of its divisors is an integer number (82931946).

Almost surely, 2^165863891 is an apocalyptic number.

165863891 is a deficient number, since it is larger than the sum of its proper divisors (1).

165863891 is an equidigital number, since it uses as much as digits as its factorization.

165863891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 47.

The square root of 165863891 is about 12878.8155899524. The cubic root of 165863891 is about 549.4362167760.

The spelling of 165863891 in words is "one hundred sixty-five million, eight hundred sixty-three thousand, eight hundred ninety-one".