11111220161 has 2 divisors, whose sum is σ = 11111220162. Its totient is φ = 11111220160.

The previous prime is 11111220073. The next prime is 11111220163. The reversal of 11111220161 is 16102211111.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10368330625 + 742889536 = 101825^2 + 27256^2 .

It is a cyclic number.

It is not a de Polignac number, because 11111220161 - 2¹⁰ = 11111219137 is a prime.

Together with 11111220163, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (11111220163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5555610080 + 5555610081.

It is an arithmetic number, because the mean of its divisors is an integer number (5555610081).

Almost surely, 2^11111220161 is an apocalyptic number.

It is an amenable number.

11111220161 is a deficient number, since it is larger than the sum of its proper divisors (1).

11111220161 is an equidigital number, since it uses as much as digits as its factorization.

11111220161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 17.

Adding to 11111220161 its reverse (16102211111), we get a palindrome (27213431272).

The spelling of 11111220161 in words is "eleven billion, one hundred eleven million, two hundred twenty thousand, one hundred sixty-one".