165381989 has 2 divisors, whose sum is σ = 165381990. Its totient is φ = 165381988.

The previous prime is 165381977. The next prime is 165381991. The reversal of 165381989 is 989183561.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 125059489 + 40322500 = 11183^2 + 6350^2 .

It is an emirp because it is prime and its reverse (989183561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165381989 - 2⁴ = 165381973 is a prime.

It is a super-2 number, since 2×165381989² = 54702404571192242, which contains 22 as substring.

Together with 165381991, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165381949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82690994 + 82690995.

It is an arithmetic number, because the mean of its divisors is an integer number (82690995).

Almost surely, 2^165381989 is an apocalyptic number.

It is an amenable number.

165381989 is a deficient number, since it is larger than the sum of its proper divisors (1).

165381989 is an equidigital number, since it uses as much as digits as its factorization.

165381989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 466560, while the sum is 50.

The square root of 165381989 is about 12860.0928845790. The cubic root of 165381989 is about 548.9035887868.

The spelling of 165381989 in words is "one hundred sixty-five million, three hundred eighty-one thousand, nine hundred eighty-nine".