21000217 has 8 divisors (see below), whose sum is σ = 24184512. Its totient is φ = 17862000.

The previous prime is 21000193. The next prime is 21000229. The reversal of 21000217 is 71200012.

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 21000217 - 2¹¹ = 20998169 is a prime.

It is a super-2 number, since 2×21000217² = 882018228094178, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000197 and 21000206.

It is not an unprimeable number, because it can be changed into a prime (21000277) 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, 10534 + ... + 12367.

It is an arithmetic number, because the mean of its divisors is an integer number (3023064).

Almost surely, 2^21000217 is an apocalyptic number.

It is an amenable number.

21000217 is a deficient number, since it is larger than the sum of its proper divisors (3184295).

21000217 is a wasteful number, since it uses less digits than its factorization.

21000217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23039.

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 21000217 is about 4582.5993715358. The cubic root of 21000217 is about 275.8933679309.

Adding to 21000217 its reverse (71200012), we get a palindrome (92200229).

The spelling of 21000217 in words is "twenty-one million, two hundred seventeen", and thus it is an aban number.