2217991 has 2 divisors, whose sum is σ = 2217992. Its totient is φ = 2217990.

The previous prime is 2217967. The next prime is 2218001. The reversal of 2217991 is 1997122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2217991 - 2⁷ = 2217863 is a prime.

It is a Chen prime.

2217991 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2217911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1108995 + 1108996.

It is an arithmetic number, because the mean of its divisors is an integer number (1108996).

2^2217991 is an apocalyptic number.

2217991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2217991 is an equidigital number, since it uses as much as digits as its factorization.

2217991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268, while the sum is 31.

The square root of 2217991 is about 1489.2921137238. The cubic root of 2217991 is about 130.4127120419.

The spelling of 2217991 in words is "two million, two hundred seventeen thousand, nine hundred ninety-one".