197809 has 8 divisors (see below), whose sum is σ = 216000. Its totient is φ = 180432.

The previous prime is 197807. The next prime is 197831. The reversal of 197809 is 908791.

197809 = T₁₀₂ + T₁₀₃ + ... + T₁₃₀.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 197809 - 2¹ = 197807 is a prime.

It is a Duffinian number.

197809 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (197803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 372 + ... + 730.

It is an arithmetic number, because the mean of its divisors is an integer number (27000).

2¹⁹⁷⁸⁰⁹ is an apocalyptic number.

197809 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

197809 is a deficient number, since it is larger than the sum of its proper divisors (18191).

197809 is a wasteful number, since it uses less digits than its factorization.

197809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407.

The product of its (nonzero) digits is 4536, while the sum is 34.

The square root of 197809 is about 444.7572371530. The cubic root of 197809 is about 58.2660194049.

The spelling of 197809 in words is "one hundred ninety-seven thousand, eight hundred nine".