21117217 has 8 divisors (see below), whose sum is σ = 23094720. Its totient is φ = 19149360.

The previous prime is 21117209. The next prime is 21117223. The reversal of 21117217 is 71271112.

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 21117217 - 2³ = 21117209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21117277) 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, 2643 + ... + 7015.

It is an arithmetic number, because the mean of its divisors is an integer number (2886840).

Almost surely, 2^21117217 is an apocalyptic number.

It is an amenable number.

21117217 is a deficient number, since it is larger than the sum of its proper divisors (1977503).

21117217 is a wasteful number, since it uses less digits than its factorization.

21117217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4823.

The product of its digits is 196, while the sum is 22.

The square root of 21117217 is about 4595.3473209323. The cubic root of 21117217 is about 276.4047874374.

Adding to 21117217 its reverse (71271112), we get a palindrome (92388329).

The spelling of 21117217 in words is "twenty-one million, one hundred seventeen thousand, two hundred seventeen".