9997 has 4 divisors (see below), whose sum is σ = 10780.
Its totient is φ = 9216.
The previous prime is 9973. The next prime is 10007. The reversal of 9997 is 7999.
9997 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7999 = 19 ⋅421.
It can be written as a sum of positive squares in 2 ways, for example, as 2601 + 7396 = 51^2 + 86^2
It is a 5-Lehmer number, since φ(9997) divides (9997-1)5.
It is a cyclic number.
It is not a de Polignac number, because 9997 - 211 = 7949 is a prime.
It is a Duffinian number.
9997 is a lucky number.
It is a nialpdrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (9907) 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 3 ways as a sum of consecutive naturals, for example, 372 + ... + 397.
It is an arithmetic number, because the mean of its divisors is an integer number (2695).
29997 is an apocalyptic number.
It is an amenable number.
9997 is a deficient number, since it is larger than the sum of its proper divisors (783).
9997 is a wasteful number, since it uses less digits than its factorization.
9997 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 782.
The product of its digits is 5103, while the sum is 34.
The square root of 9997 is about 99.9849988748.
The cubic root of 9997 is about 21.5421922501.
It can be divided in two parts, 99 and 97, that added together give a square (196 = 142).
The spelling of 9997 in words is "nine thousand, nine hundred ninety-seven".