891871691 has 2 divisors, whose sum is σ = 891871692. Its totient is φ = 891871690.

The previous prime is 891871679. The next prime is 891871693. The reversal of 891871691 is 196178198.

891871691 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 is a cyclic number.

It is not a de Polignac number, because 891871691 - 2¹⁰ = 891870667 is a prime.

It is a super-2 number, since 2×891871691² = 1590870226414398962, which contains 22 as substring.

Together with 891871693, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (891871693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445935845 + 445935846.

It is an arithmetic number, because the mean of its divisors is an integer number (445935846).

Almost surely, 2^891871691 is an apocalyptic number.

891871691 is a deficient number, since it is larger than the sum of its proper divisors (1).

891871691 is an equidigital number, since it uses as much as digits as its factorization.

891871691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 50.

The square root of 891871691 is about 29864.2209173452. The cubic root of 891871691 is about 962.5739990557.

The spelling of 891871691 in words is "eight hundred ninety-one million, eight hundred seventy-one thousand, six hundred ninety-one".