221799817 has 2 divisors, whose sum is σ = 221799818. Its totient is φ = 221799816.

The previous prime is 221799803. The next prime is 221799829. The reversal of 221799817 is 718997122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 183223296 + 38576521 = 13536^2 + 6211^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221799817 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221799857) 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, 110899908 + 110899909.

It is an arithmetic number, because the mean of its divisors is an integer number (110899909).

Almost surely, 2^221799817 is an apocalyptic number.

It is an amenable number.

221799817 is a deficient number, since it is larger than the sum of its proper divisors (1).

221799817 is an equidigital number, since it uses as much as digits as its factorization.

221799817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127008, while the sum is 46.

The square root of 221799817 is about 14892.9452090579. The cubic root of 221799817 is about 605.3228402400.

The spelling of 221799817 in words is "two hundred twenty-one million, seven hundred ninety-nine thousand, eight hundred seventeen".