19917 has 6 divisors (see below), whose sum is σ = 28782. Its totient is φ = 13272.

The previous prime is 19913. The next prime is 19919. The reversal of 19917 is 71991.

It can be written as a sum of positive squares in only one way, i.e., 19881 + 36 = 141^2 + 6^2 .

It is not a de Polignac number, because 19917 - 2² = 19913 is a prime.

19917 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 19917.

It is not an unprimeable number, because it can be changed into a prime (19913) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1098 + ... + 1115.

It is an arithmetic number, because the mean of its divisors is an integer number (4797).

2¹⁹⁹¹⁷ is an apocalyptic number.

It is an amenable number.

19917 is a deficient number, since it is larger than the sum of its proper divisors (8865).

19917 is a wasteful number, since it uses less digits than its factorization.

19917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2219 (or 2216 counting only the distinct ones).

The product of its digits is 567, while the sum is 27.

The square root of 19917 is about 141.1276018361. The cubic root of 19917 is about 27.1065746588.

It can be divided in two parts, 199 and 17, that added together give a cube (216 = 6³).

The spelling of 19917 in words is "nineteen thousand, nine hundred seventeen".