165819919 has 2 divisors, whose sum is σ = 165819920. Its totient is φ = 165819918.

The previous prime is 165819893. The next prime is 165819943. The reversal of 165819919 is 919918561.

165819919 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 an emirp because it is prime and its reverse (919918561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165819919 - 2⁷ = 165819791 is a prime.

It is a super-3 number, since 3×165819919³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165819959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82909959 + 82909960.

It is an arithmetic number, because the mean of its divisors is an integer number (82909960).

Almost surely, 2^165819919 is an apocalyptic number.

165819919 is a deficient number, since it is larger than the sum of its proper divisors (1).

165819919 is an equidigital number, since it uses as much as digits as its factorization.

165819919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 174960, while the sum is 49.

The square root of 165819919 is about 12877.1083322305. The cubic root of 165819919 is about 549.3876590007.

The spelling of 165819919 in words is "one hundred sixty-five million, eight hundred nineteen thousand, nine hundred nineteen".