2166221 has 2 divisors, whose sum is σ = 2166222. Its totient is φ = 2166220.

The previous prime is 2166179. The next prime is 2166233. The reversal of 2166221 is 1226612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1188100 + 978121 = 1090^2 + 989^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2166221 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2166193 and 2166202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2166251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1083110 + 1083111.

It is an arithmetic number, because the mean of its divisors is an integer number (1083111).

2^2166221 is an apocalyptic number.

It is an amenable number.

2166221 is a deficient number, since it is larger than the sum of its proper divisors (1).

2166221 is an equidigital number, since it uses as much as digits as its factorization.

2166221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 20.

The square root of 2166221 is about 1471.8087511630. The cubic root of 2166221 is about 129.3900618807.

The spelling of 2166221 in words is "two million, one hundred sixty-six thousand, two hundred twenty-one".