221742161 has 2 divisors, whose sum is σ = 221742162. Its totient is φ = 221742160.

The previous prime is 221742151. The next prime is 221742181. The reversal of 221742161 is 161247122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 212255761 + 9486400 = 14569^2 + 3080^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221742161 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221742161.

It is not a weakly prime, because it can be changed into another prime (221742121) 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, 110871080 + 110871081.

It is an arithmetic number, because the mean of its divisors is an integer number (110871081).

Almost surely, 2^221742161 is an apocalyptic number.

It is an amenable number.

221742161 is a deficient number, since it is larger than the sum of its proper divisors (1).

221742161 is an equidigital number, since it uses as much as digits as its factorization.

221742161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1344, while the sum is 26.

The square root of 221742161 is about 14891.0094016490. The cubic root of 221742161 is about 605.2703852550.

Adding to 221742161 its reverse (161247122), we get a palindrome (382989283).

The spelling of 221742161 in words is "two hundred twenty-one million, seven hundred forty-two thousand, one hundred sixty-one".