21297 has 8 divisors (see below), whose sum is σ = 29440. Its totient is φ = 13680.

The previous prime is 21283. The next prime is 21313. The reversal of 21297 is 79212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21297 - 2⁷ = 21169 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21227) 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 7 ways as a sum of consecutive naturals, for example, 22 + ... + 207.

It is an arithmetic number, because the mean of its divisors is an integer number (3680).

2²¹²⁹⁷ is an apocalyptic number.

It is an amenable number.

21297 is a deficient number, since it is larger than the sum of its proper divisors (8143).

21297 is a wasteful number, since it uses less digits than its factorization.

21297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263.

The product of its digits is 252, while the sum is 21.

The square root of 21297 is about 145.9349170007. The cubic root of 21297 is about 27.7186969480.

The spelling of 21297 in words is "twenty-one thousand, two hundred ninety-seven".