165783121 has 12 divisors (see below), whose sum is σ = 195178032. Its totient is φ = 140384328.

The previous prime is 165783077. The next prime is 165783127. The reversal of 165783121 is 121387561.

It is a happy number.

It is not a de Polignac number, because 165783121 - 2¹¹ = 165781073 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165783127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16315 + ... + 24448.

It is an arithmetic number, because the mean of its divisors is an integer number (16264836).

Almost surely, 2^165783121 is an apocalyptic number.

It is an amenable number.

165783121 is a deficient number, since it is larger than the sum of its proper divisors (29394911).

165783121 is an equidigital number, since it uses as much as digits as its factorization.

165783121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40860 (or 40853 counting only the distinct ones).

The product of its digits is 10080, while the sum is 34.

The square root of 165783121 is about 12875.6794383830. The cubic root of 165783121 is about 549.3470167931.

The spelling of 165783121 in words is "one hundred sixty-five million, seven hundred eighty-three thousand, one hundred twenty-one".