165712121 has 4 divisors (see below), whose sum is σ = 165740544. Its totient is φ = 165683700.

The previous prime is 165712109. The next prime is 165712123. The reversal of 165712121 is 121217561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 165712121 - 2¹⁴ = 165695737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165712123) 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 3 ways as a sum of consecutive naturals, for example, 1925 + ... + 18306.

It is an arithmetic number, because the mean of its divisors is an integer number (41435136).

Almost surely, 2^165712121 is an apocalyptic number.

It is an amenable number.

165712121 is a deficient number, since it is larger than the sum of its proper divisors (28423).

165712121 is an equidigital number, since it uses as much as digits as its factorization.

165712121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28422.

The product of its digits is 840, while the sum is 26.

The square root of 165712121 is about 12872.9220070658. The cubic root of 165712121 is about 549.2685825767.

Adding to 165712121 its reverse (121217561), we get a palindrome (286929682).

The spelling of 165712121 in words is "one hundred sixty-five million, seven hundred twelve thousand, one hundred twenty-one".