198581 has 4 divisors (see below), whose sum is σ = 199500. Its totient is φ = 197664.
The previous prime is 198571. The next prime is 198589. The reversal of 198581 is 185891.
It is a happy number.
198581 is nontrivially palindromic in base 14.
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: 185891 = 211 ⋅881.
It can be written as a sum of positive squares in 2 ways, for example, as 87025 + 111556 = 295^2 + 334^2 .
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-198581 is a prime.
It is a super-2 number, since 2×1985812 = 78868827122, which contains 22 as substring.
It is a Duffinian number.
198581 is an undulating number in base 14.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (198589) 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, 65 + ... + 633.
It is an arithmetic number, because the mean of its divisors is an integer number (49875).
2198581 is an apocalyptic number.
It is an amenable number.
198581 is a deficient number, since it is larger than the sum of its proper divisors (919).
198581 is an equidigital number, since it uses as much as digits as its factorization.
198581 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 918.
The product of its digits is 2880, while the sum is 32.
The square root of 198581 is about 445.6242812056. The cubic root of 198581 is about 58.3417203360.
The spelling of 198581 in words is "one hundred ninety-eight thousand, five hundred eighty-one".
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