171221221 has 2 divisors, whose sum is σ = 171221222. Its totient is φ = 171221220.

The previous prime is 171221201. The next prime is 171221261. The reversal of 171221221 is 122122171.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90041121 + 81180100 = 9489^2 + 9010^2 .

It is a cyclic number.

It is not a de Polignac number, because 171221221 - 2¹⁷ = 171090149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (171221201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85610610 + 85610611.

It is an arithmetic number, because the mean of its divisors is an integer number (85610611).

Almost surely, 2^171221221 is an apocalyptic number.

It is an amenable number.

171221221 is a deficient number, since it is larger than the sum of its proper divisors (1).

171221221 is an equidigital number, since it uses as much as digits as its factorization.

171221221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 112, while the sum is 19.

The square root of 171221221 is about 13085.1526930334. The cubic root of 171221221 is about 555.2891613322.

Adding to 171221221 its reverse (122122171), we get a palindrome (293343392).

The spelling of 171221221 in words is "one hundred seventy-one million, two hundred twenty-one thousand, two hundred twenty-one".