281221217 has 2 divisors, whose sum is σ = 281221218. Its totient is φ = 281221216.

The previous prime is 281221211. The next prime is 281221219. The reversal of 281221217 is 712122182.

281221217 is nontrivially palindromic in base 2.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 143017681 + 138203536 = 11959^2 + 11756^2 .

It is a cyclic number.

It is not a de Polignac number, because 281221217 - 2¹⁰ = 281220193 is a prime.

It is a super-2 number, since 2×281221217² = 158170745781922178, which contains 22 as substring.

Together with 281221219, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (281221211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 140610608 + 140610609.

It is an arithmetic number, because the mean of its divisors is an integer number (140610609).

Almost surely, 2^281221217 is an apocalyptic number.

It is an amenable number.

281221217 is a deficient number, since it is larger than the sum of its proper divisors (1).

281221217 is an equidigital number, since it uses as much as digits as its factorization.

281221217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 896, while the sum is 26.

The square root of 281221217 is about 16769.6516660305. The cubic root of 281221217 is about 655.1629973306.

Adding to 281221217 its reverse (712122182), we get a palindrome (993343399).

The spelling of 281221217 in words is "two hundred eighty-one million, two hundred twenty-one thousand, two hundred seventeen".