2221991 has 2 divisors, whose sum is σ = 2221992. Its totient is φ = 2221990.

The previous prime is 2221981. The next prime is 2221997. The reversal of 2221991 is 1991222.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2221991 - 2¹⁸ = 1959847 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 2221991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2221997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1110995 + 1110996.

It is an arithmetic number, because the mean of its divisors is an integer number (1110996).

2^2221991 is an apocalyptic number.

2221991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2221991 is an equidigital number, since it uses as much as digits as its factorization.

2221991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648, while the sum is 26.

The square root of 2221991 is about 1490.6344286914. The cubic root of 2221991 is about 130.4910618600.

The spelling of 2221991 in words is "two million, two hundred twenty-one thousand, nine hundred ninety-one".