161366221 has 4 divisors (see below), whose sum is σ = 169859200. Its totient is φ = 152873244.

The previous prime is 161366203. The next prime is 161366267. The reversal of 161366221 is 122663161.

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 161366221 - 2⁵ = 161366189 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161366221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161366021) 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, 4246461 + ... + 4246498.

It is an arithmetic number, because the mean of its divisors is an integer number (42464800).

Almost surely, 2^161366221 is an apocalyptic number.

It is an amenable number.

161366221 is a deficient number, since it is larger than the sum of its proper divisors (8492979).

161366221 is an equidigital number, since it uses as much as digits as its factorization.

161366221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8492978.

The product of its digits is 2592, while the sum is 28.

The square root of 161366221 is about 12703.0004723294. Note that the first 3 decimals coincide. The cubic root of 161366221 is about 544.4243519341.

The spelling of 161366221 in words is "one hundred sixty-one million, three hundred sixty-six thousand, two hundred twenty-one".