165453721 has 2 divisors, whose sum is σ = 165453722. Its totient is φ = 165453720.

The previous prime is 165453719. The next prime is 165453733. The reversal of 165453721 is 127354561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165405321 + 48400 = 12861^2 + 220^2 .

It is an emirp because it is prime and its reverse (127354561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165453721 - 2¹ = 165453719 is a prime.

Together with 165453719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (165453791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82726860 + 82726861.

It is an arithmetic number, because the mean of its divisors is an integer number (82726861).

Almost surely, 2^165453721 is an apocalyptic number.

It is an amenable number.

165453721 is a deficient number, since it is larger than the sum of its proper divisors (1).

165453721 is an equidigital number, since it uses as much as digits as its factorization.

165453721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25200, while the sum is 34.

The square root of 165453721 is about 12862.8815200949. The cubic root of 165453721 is about 548.9829369295.

The spelling of 165453721 in words is "one hundred sixty-five million, four hundred fifty-three thousand, seven hundred twenty-one".