221345217 has 20 divisors (see below), whose sum is σ = 332123220. Its totient is φ = 146906784.

The previous prime is 221345207. The next prime is 221345227. The reversal of 221345217 is 712543122.

221345217 = 454² + 455² + ... + 911².

221345217 is a `hidden beast` number, since 2 + 2 + 134 + 521 + 7 = 666.

221345217 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (221345207) and next prime (221345227).

It can be written as a sum of positive squares in 2 ways, for example, as 197374401 + 23970816 = 14049^2 + 4896^2 .

It is not a de Polignac number, because 221345217 - 2⁸ = 221344961 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (221345207) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 12583 + ... + 24515.

It is an arithmetic number, because the mean of its divisors is an integer number (16606161).

Almost surely, 2^221345217 is an apocalyptic number.

221345217 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

221345217 is a deficient number, since it is larger than the sum of its proper divisors (110778003).

221345217 is a wasteful number, since it uses less digits than its factorization.

221345217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12174 (or 12165 counting only the distinct ones).

The product of its digits is 3360, while the sum is 27.

The square root of 221345217 is about 14877.6751207976. The cubic root of 221345217 is about 604.9090016358.

Adding to 221345217 its reverse (712543122), we get a palindrome (933888339).

The spelling of 221345217 in words is "two hundred twenty-one million, three hundred forty-five thousand, two hundred seventeen".