1091671991 has 2 divisors, whose sum is σ = 1091671992. Its totient is φ = 1091671990.

The previous prime is 1091671981. The next prime is 1091671993. The reversal of 1091671991 is 1991761901.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1091671991 - 2⁶ = 1091671927 is a prime.

Together with 1091671993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1091671993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 545835995 + 545835996.

It is an arithmetic number, because the mean of its divisors is an integer number (545835996).

Almost surely, 2^1091671991 is an apocalyptic number.

1091671991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1091671991 is an equidigital number, since it uses as much as digits as its factorization.

1091671991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30618, while the sum is 44.

The square root of 1091671991 is about 33040.4599090267. The cubic root of 1091671991 is about 1029.6684108734.

The spelling of 1091671991 in words is "one billion, ninety-one million, six hundred seventy-one thousand, nine hundred ninety-one".