165702221 has 4 divisors (see below), whose sum is σ = 168828732. Its totient is φ = 162575712.

The previous prime is 165702217. The next prime is 165702227. The reversal of 165702221 is 122207561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122207561 = 7 ⋅17458223.

It can be written as a sum of positive squares in 2 ways, for example, as 48846121 + 116856100 = 6989^2 + 10810^2 .

It is a cyclic number.

It is not a de Polignac number, because 165702221 - 2² = 165702217 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 (165702227) 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, 1563176 + ... + 1563281.

It is an arithmetic number, because the mean of its divisors is an integer number (42207183).

Almost surely, 2^165702221 is an apocalyptic number.

It is an amenable number.

165702221 is a deficient number, since it is larger than the sum of its proper divisors (3126511).

165702221 is an equidigital number, since it uses as much as digits as its factorization.

165702221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3126510.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 165702221 is about 12872.5374732412. The cubic root of 165702221 is about 549.2576441951.

Adding to 165702221 its reverse (122207561), we get a palindrome (287909782).

The spelling of 165702221 in words is "one hundred sixty-five million, seven hundred two thousand, two hundred twenty-one".