11111223456661 has 2 divisors, whose sum is σ = 11111223456662. Its totient is φ = 11111223456660.

The previous prime is 11111223456637. The next prime is 11111223456677. The reversal of 11111223456661 is 16665432211111.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9917271688900 + 1193951767761 = 3149170^2 + 1092681^2 .

It is a cyclic number.

It is not a de Polignac number, because 11111223456661 - 2⁷ = 11111223456533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11111223456631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5555611728330 + 5555611728331.

It is an arithmetic number, because the mean of its divisors is an integer number (5555611728331).

Almost surely, 2^{11111223456661} is an apocalyptic number.

It is an amenable number.

11111223456661 is a deficient number, since it is larger than the sum of its proper divisors (1).

11111223456661 is an equidigital number, since it uses as much as digits as its factorization.

11111223456661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 40.

Adding to 11111223456661 its reverse (16665432211111), we get a palindrome (27776655667772).

The spelling of 11111223456661 in words is "eleven trillion, one hundred eleven billion, two hundred twenty-three million, four hundred fifty-six thousand, six hundred sixty-one".