221224537 has 2 divisors, whose sum is σ = 221224538. Its totient is φ = 221224536.

The previous prime is 221224483. The next prime is 221224559. The reversal of 221224537 is 735422122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208629136 + 12595401 = 14444^2 + 3549^2 .

It is a cyclic number.

It is not a de Polignac number, because 221224537 - 2¹⁵ = 221191769 is a prime.

It is not a weakly prime, because it can be changed into another prime (221224337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110612268 + 110612269.

It is an arithmetic number, because the mean of its divisors is an integer number (110612269).

Almost surely, 2^221224537 is an apocalyptic number.

It is an amenable number.

221224537 is a deficient number, since it is larger than the sum of its proper divisors (1).

221224537 is an equidigital number, since it uses as much as digits as its factorization.

221224537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6720, while the sum is 28.

The square root of 221224537 is about 14873.6188266340. The cubic root of 221224537 is about 604.7990471641.

Adding to 221224537 its reverse (735422122), we get a palindrome (956646659).

The spelling of 221224537 in words is "two hundred twenty-one million, two hundred twenty-four thousand, five hundred thirty-seven".