16166221 has 4 divisors (see below), whose sum is σ = 16687744. Its totient is φ = 15644700.

The previous prime is 16166209. The next prime is 16166243. The reversal of 16166221 is 12266161.

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 16166221 - 2²³ = 7777613 is a prime.

It is a super-2 number, since 2×16166221² = 522693402841682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16166291) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260715 + ... + 260776.

It is an arithmetic number, because the mean of its divisors is an integer number (4171936).

Almost surely, 2^16166221 is an apocalyptic number.

It is an amenable number.

16166221 is a deficient number, since it is larger than the sum of its proper divisors (521523).

16166221 is an equidigital number, since it uses as much as digits as its factorization.

16166221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 521522.

The product of its digits is 864, while the sum is 25.

The square root of 16166221 is about 4020.7239397899. The cubic root of 16166221 is about 252.8538110911.

The spelling of 16166221 in words is "sixteen million, one hundred sixty-six thousand, two hundred twenty-one".