2291991 has 16 divisors (see below), whose sum is σ = 3485664. Its totient is φ = 1327104.

The previous prime is 2291987. The next prime is 2291999. The reversal of 2291991 is 1991922.

It is not a de Polignac number, because 2291991 - 2² = 2291987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2291999) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1066 + ... + 2391.

It is an arithmetic number, because the mean of its divisors is an integer number (217854).

2^2291991 is an apocalyptic number.

2291991 is a deficient number, since it is larger than the sum of its proper divisors (1193673).

2291991 is a wasteful number, since it uses less digits than its factorization.

2291991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3490.

The product of its digits is 2916, while the sum is 33.

The square root of 2291991 is about 1513.9322970331. The cubic root of 2291991 is about 131.8472176300.

The spelling of 2291991 in words is "two million, two hundred ninety-one thousand, nine hundred ninety-one".