1220111891 has 2 divisors, whose sum is σ = 1220111892. Its totient is φ = 1220111890.

The previous prime is 1220111833. The next prime is 1220111897. The reversal of 1220111891 is 1981110221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1220111891 - 2¹⁰ = 1220110867 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1220111891.

It is not a weakly prime, because it can be changed into another prime (1220111897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610055945 + 610055946.

It is an arithmetic number, because the mean of its divisors is an integer number (610055946).

Almost surely, 2^1220111891 is an apocalyptic number.

1220111891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1220111891 is an equidigital number, since it uses as much as digits as its factorization.

1220111891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 26.

The square root of 1220111891 is about 34930.1000714284. The cubic root of 1220111891 is about 1068.5623955055.

The spelling of 1220111891 in words is "one billion, two hundred twenty million, one hundred eleven thousand, eight hundred ninety-one".