891191669 has 2 divisors, whose sum is σ = 891191670. Its totient is φ = 891191668.

The previous prime is 891191647. The next prime is 891191687. The reversal of 891191669 is 966191198.

891191669 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 878411044 + 12780625 = 29638^2 + 3575^2 .

It is a cyclic number.

It is not a de Polignac number, because 891191669 - 2¹² = 891187573 is a prime.

It is a super-2 number, since 2×891191669² = 1588445181790011122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (891191699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445595834 + 445595835.

It is an arithmetic number, because the mean of its divisors is an integer number (445595835).

Almost surely, 2^891191669 is an apocalyptic number.

It is an amenable number.

891191669 is a deficient number, since it is larger than the sum of its proper divisors (1).

891191669 is an equidigital number, since it uses as much as digits as its factorization.

891191669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 209952, while the sum is 50.

The square root of 891191669 is about 29852.8335171052. The cubic root of 891191669 is about 962.3292934790.

The spelling of 891191669 in words is "eight hundred ninety-one million, one hundred ninety-one thousand, six hundred sixty-nine".