997891 has 2 divisors, whose sum is σ = 997892.
Its totient is φ = 997890.
The previous prime is 997889. The next prime is 997897. The reversal of 997891 is 198799.
997891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 997891 - 21 = 997889 is a prime.
Together with 997889, it forms a pair of twin primes.
It is not a weakly prime, because it can be changed into another prime (997897) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498945 + 498946.
It is an arithmetic number, because the mean of its divisors is an integer number (498946).
2997891 is an apocalyptic number.
997891 is a deficient number, since it is larger than the sum of its proper divisors (1).
997891 is an equidigital number, since it uses as much as digits as its factorization.
997891 is an evil number, because the sum of its binary digits is even.
The product of its digits is 40824, while the sum is 43.
The square root of 997891 is about 998.9449434278.
The cubic root of 997891 is about 99.9296505211.
The spelling of 997891 in words is "nine hundred ninety-seven thousand, eight hundred ninety-one".