221621233 has 2 divisors, whose sum is σ = 221621234. Its totient is φ = 221621232.

The previous prime is 221621227. The next prime is 221621243. The reversal of 221621233 is 332126122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 178810384 + 42810849 = 13372^2 + 6543^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221621233 is a prime.

It is not a weakly prime, because it can be changed into another prime (221621243) 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, 110810616 + 110810617.

It is an arithmetic number, because the mean of its divisors is an integer number (110810617).

Almost surely, 2^221621233 is an apocalyptic number.

It is an amenable number.

221621233 is a deficient number, since it is larger than the sum of its proper divisors (1).

221621233 is an equidigital number, since it uses as much as digits as its factorization.

221621233 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 22.

The square root of 221621233 is about 14886.9484112762. The cubic root of 221621233 is about 605.1603363489.

Adding to 221621233 its reverse (332126122), we get a palindrome (553747355).

The spelling of 221621233 in words is "two hundred twenty-one million, six hundred twenty-one thousand, two hundred thirty-three".