198691 has 4 divisors (see below), whose sum is σ = 199584. Its totient is φ = 197800.

The previous prime is 198689. The next prime is 198701. The reversal of 198691 is 196891.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 196891 = 401 ⋅491.

It is a cyclic number.

It is not a de Polignac number, because 198691 - 2¹ = 198689 is a prime.

It is a super-2 number, since 2×198691² = 78956226962, which contains 22 as substring.

It is a Duffinian number.

198691 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (198641) 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, 201 + ... + 661.

It is an arithmetic number, because the mean of its divisors is an integer number (49896).

2¹⁹⁸⁶⁹¹ is an apocalyptic number.

198691 is a deficient number, since it is larger than the sum of its proper divisors (893).

198691 is an equidigital number, since it uses as much as digits as its factorization.

198691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 892.

The product of its digits is 3888, while the sum is 34.

The square root of 198691 is about 445.7476864775. The cubic root of 198691 is about 58.3524907599.

The spelling of 198691 in words is "one hundred ninety-eight thousand, six hundred ninety-one".