21197 has 8 divisors (see below), whose sum is σ = 24192. Its totient is φ = 18400.

The previous prime is 21193. The next prime is 21211. The reversal of 21197 is 79112.

21197 is nontrivially palindromic in base 8.

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

It is a cyclic number.

It is not a de Polignac number, because 21197 - 2² = 21193 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21191) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 428 + ... + 474.

It is an arithmetic number, because the mean of its divisors is an integer number (3024).

2²¹¹⁹⁷ is an apocalyptic number.

It is an amenable number.

21197 is a deficient number, since it is larger than the sum of its proper divisors (2995).

21197 is a wasteful number, since it uses less digits than its factorization.

21197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99.

The product of its digits is 126, while the sum is 20.

The square root of 21197 is about 145.5918953788. The cubic root of 21197 is about 27.6752445137.

The spelling of 21197 in words is "twenty-one thousand, one hundred ninety-seven".