19665 has 24 divisors (see below), whose sum is σ = 37440. Its totient is φ = 9504.
The previous prime is 19661. The next prime is 19681. The reversal of 19665 is 56691.
It is not a de Polignac number, because 19665 - 22 = 19661 is a prime.
It is a plaindrome in base 7.
It is a nialpdrome in base 3.
It is a zygodrome in base 7.
It is not an unprimeable number, because it can be changed into a prime (19661) 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 23 ways as a sum of consecutive naturals, for example, 844 + ... + 866.
It is an arithmetic number, because the mean of its divisors is an integer number (1560).
219665 is an apocalyptic number.
19665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.
It is an amenable number.
19665 is a deficient number, since it is larger than the sum of its proper divisors (17775).
19665 is a wasteful number, since it uses less digits than its factorization.
19665 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 53 (or 50 counting only the distinct ones).
The product of its digits is 1620, while the sum is 27.
The square root of 19665 is about 140.2319507102. The cubic root of 19665 is about 26.9917670371.
The spelling of 19665 in words is "nineteen thousand, six hundred sixty-five".
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