2191219991 has 2 divisors, whose sum is σ = 2191219992. Its totient is φ = 2191219990.

The previous prime is 2191219909. The next prime is 2191220021. The reversal of 2191219991 is 1999121912.

2191219991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2191219991 - 2¹⁴ = 2191203607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2191219391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1095609995 + 1095609996.

It is an arithmetic number, because the mean of its divisors is an integer number (1095609996).

Almost surely, 2^2191219991 is an apocalyptic number.

2191219991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191219991 is an equidigital number, since it uses as much as digits as its factorization.

2191219991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26244, while the sum is 44.

The square root of 2191219991 is about 46810.4688184171. The cubic root of 2191219991 is about 1298.8589575487.

The spelling of 2191219991 in words is "two billion, one hundred ninety-one million, two hundred nineteen thousand, nine hundred ninety-one".