228161221 has 2 divisors, whose sum is σ = 228161222. Its totient is φ = 228161220.

The previous prime is 228161191. The next prime is 228161239. The reversal of 228161221 is 122161822.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 228161025 + 196 = 15105^2 + 14^2 .

It is a cyclic number.

It is not a de Polignac number, because 228161221 - 2⁵ = 228161189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (228161251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 114080610 + 114080611.

It is an arithmetic number, because the mean of its divisors is an integer number (114080611).

Almost surely, 2^228161221 is an apocalyptic number.

It is an amenable number.

228161221 is a deficient number, since it is larger than the sum of its proper divisors (1).

228161221 is an equidigital number, since it uses as much as digits as its factorization.

228161221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 25.

The square root of 228161221 is about 15105.0064879165. The cubic root of 228161221 is about 611.0554343019.

The spelling of 228161221 in words is "two hundred twenty-eight million, one hundred sixty-one thousand, two hundred twenty-one".