197891 has 2 divisors, whose sum is σ = 197892. Its totient is φ = 197890.

The previous prime is 197887. The next prime is 197893. The reversal of 197891 is 198791.

197891 is nontrivially palindromic in base 16.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 197891 - 2² = 197887 is a prime.

Together with 197893, it forms a pair of twin primes.

It is a Chen prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (197893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98945 + 98946.

It is an arithmetic number, because the mean of its divisors is an integer number (98946).

2¹⁹⁷⁸⁹¹ is an apocalyptic number.

197891 is a deficient number, since it is larger than the sum of its proper divisors (1).

197891 is an equidigital number, since it uses as much as digits as its factorization.

197891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4536, while the sum is 35.

The square root of 197891 is about 444.8494127230. The cubic root of 197891 is about 58.2740695165.

Subtracting 197891 from its reverse (198791), we obtain a square (900 = 30²).

The spelling of 197891 in words is "one hundred ninety-seven thousand, eight hundred ninety-one".