221281 has 2 divisors, whose sum is σ = 221282. Its totient is φ = 221280.

The previous prime is 221261. The next prime is 221303. The reversal of 221281 is 182122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 140625 + 80656 = 375^2 + 284^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221281 is a prime.

It is a super-2 number, since 2×221281² = 97930561922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (221201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110640 + 110641.

It is an arithmetic number, because the mean of its divisors is an integer number (110641).

2²²¹²⁸¹ is an apocalyptic number.

It is an amenable number.

221281 is a deficient number, since it is larger than the sum of its proper divisors (1).

221281 is an equidigital number, since it uses as much as digits as its factorization.

221281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64, while the sum is 16.

The square root of 221281 is about 470.4051445297. The cubic root of 221281 is about 60.4850496948.

It can be divided in two parts, 22 and 1281, that multiplied together give a palindrome (28182).

The spelling of 221281 in words is "two hundred twenty-one thousand, two hundred eighty-one".