221815249 has 2 divisors, whose sum is σ = 221815250. Its totient is φ = 221815248.

The previous prime is 221815241. The next prime is 221815273. The reversal of 221815249 is 942518122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120450625 + 101364624 = 10975^2 + 10068^2 .

It is a cyclic number.

It is not a de Polignac number, because 221815249 - 2³ = 221815241 is a prime.

It is not a weakly prime, because it can be changed into another prime (221815241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110907624 + 110907625.

It is an arithmetic number, because the mean of its divisors is an integer number (110907625).

Almost surely, 2^221815249 is an apocalyptic number.

It is an amenable number.

221815249 is a deficient number, since it is larger than the sum of its proper divisors (1).

221815249 is an equidigital number, since it uses as much as digits as its factorization.

221815249 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 34.

The square root of 221815249 is about 14893.4632977021. The cubic root of 221815249 is about 605.3368786126.

The spelling of 221815249 in words is "two hundred twenty-one million, eight hundred fifteen thousand, two hundred forty-nine".