111221222121991 has 2 divisors, whose sum is σ = 111221222121992. Its totient is φ = 111221222121990.

The previous prime is 111221222121949. The next prime is 111221222122141. The reversal of 111221222121991 is 199121222122111.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-111221222121991 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 111221222121991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111221222101991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55610611060995 + 55610611060996.

It is an arithmetic number, because the mean of its divisors is an integer number (55610611060996).

Almost surely, 2^{111221222121991} is an apocalyptic number.

111221222121991 is a deficient number, since it is larger than the sum of its proper divisors (1).

111221222121991 is an equidigital number, since it uses as much as digits as its factorization.

111221222121991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 37.

The spelling of 111221222121991 in words is "one hundred eleven trillion, two hundred twenty-one billion, two hundred twenty-two million, one hundred twenty-one thousand, nine hundred ninety-one".