221811281 has 2 divisors, whose sum is σ = 221811282. Its totient is φ = 221811280.

The previous prime is 221811277. The next prime is 221811323. The reversal of 221811281 is 182118122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 167935681 + 53875600 = 12959^2 + 7340^2 .

It is a cyclic number.

It is not a de Polignac number, because 221811281 - 2² = 221811277 is a prime.

It is a super-2 number, since 2×221811281² = 98400488757721922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221811281.

It is not a weakly prime, because it can be changed into another prime (221811181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110905640 + 110905641.

It is an arithmetic number, because the mean of its divisors is an integer number (110905641).

Almost surely, 2^221811281 is an apocalyptic number.

It is an amenable number.

221811281 is a deficient number, since it is larger than the sum of its proper divisors (1).

221811281 is an equidigital number, since it uses as much as digits as its factorization.

221811281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 512, while the sum is 26.

The square root of 221811281 is about 14893.3300843028. The cubic root of 221811281 is about 605.3332690154. Note that the first 3 decimals are identical.

The spelling of 221811281 in words is "two hundred twenty-one million, eight hundred eleven thousand, two hundred eighty-one".