197905 has 4 divisors (see below), whose sum is σ = 237492. Its totient is φ = 158320.

The previous prime is 197893. The next prime is 197909. The reversal of 197905 is 509791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 509791 = 29 ⋅17579.

It can be written as a sum of positive squares in 2 ways, for example, as 103041 + 94864 = 321^2 + 308^2 .

It is not a de Polignac number, because 197905 - 2¹³ = 189713 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

197905 is a lucky number.

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (197909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19786 + ... + 19795.

It is an arithmetic number, because the mean of its divisors is an integer number (59373).

2¹⁹⁷⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

197905 is a deficient number, since it is larger than the sum of its proper divisors (39587).

197905 is an equidigital number, since it uses as much as digits as its factorization.

197905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39586.

The product of its (nonzero) digits is 2835, while the sum is 31.

The square root of 197905 is about 444.8651481067. The cubic root of 197905 is about 58.2754437035.

The spelling of 197905 in words is "one hundred ninety-seven thousand, nine hundred five".