165726221 has 4 divisors (see below), whose sum is σ = 168535200. Its totient is φ = 162917244.

The previous prime is 165726181. The next prime is 165726233. The reversal of 165726221 is 122627561.

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 165726221 - 2¹⁴ = 165709837 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165726521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1404401 + ... + 1404518.

It is an arithmetic number, because the mean of its divisors is an integer number (42133800).

Almost surely, 2^165726221 is an apocalyptic number.

It is an amenable number.

165726221 is a deficient number, since it is larger than the sum of its proper divisors (2808979).

165726221 is an equidigital number, since it uses as much as digits as its factorization.

165726221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2808978.

The product of its digits is 10080, while the sum is 32.

The square root of 165726221 is about 12873.4696566233. The cubic root of 165726221 is about 549.2841607318.

The spelling of 165726221 in words is "one hundred sixty-five million, seven hundred twenty-six thousand, two hundred twenty-one".