221365217 has 2 divisors, whose sum is σ = 221365218. Its totient is φ = 221365216.

The previous prime is 221365171. The next prime is 221365223. The reversal of 221365217 is 712563122.

It is a happy number.

221365217 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 209641441 + 11723776 = 14479^2 + 3424^2 .

It is a cyclic number.

It is not a de Polignac number, because 221365217 - 2¹⁴ = 221348833 is a prime.

It is a Chen prime.

It is equal to p_12193571 and since 221365217 and 12193571 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221365217.

It is not a weakly prime, because it can be changed into another prime (221365297) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110682608 + 110682609.

It is an arithmetic number, because the mean of its divisors is an integer number (110682609).

Almost surely, 2^221365217 is an apocalyptic number.

It is an amenable number.

221365217 is a deficient number, since it is larger than the sum of its proper divisors (1).

221365217 is an equidigital number, since it uses as much as digits as its factorization.

221365217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 29.

The square root of 221365217 is about 14878.3472536435. The cubic root of 221365217 is about 604.9272202596.

The spelling of 221365217 in words is "two hundred twenty-one million, three hundred sixty-five thousand, two hundred seventeen".