1111991 has 2 divisors, whose sum is σ = 1111992. Its totient is φ = 1111990.

The previous prime is 1111967. The next prime is 1112003. The reversal of 1111991 is 1991111.

It is a happy number.

It is a strong prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1661111 and 1111661.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1111991 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1111921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 555995 + 555996.

It is an arithmetic number, because the mean of its divisors is an integer number (555996).

2^1111991 is an apocalyptic number.

1111991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1111991 is an equidigital number, since it uses as much as digits as its factorization.

1111991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81, while the sum is 23.

The square root of 1111991 is about 1054.5098387403. The cubic root of 1111991 is about 103.6017498450.

The spelling of 1111991 in words is "one million, one hundred eleven thousand, nine hundred ninety-one".