20217517 has 4 divisors (see below), whose sum is σ = 20228416. Its totient is φ = 20206620.

The previous prime is 20217493. The next prime is 20217523. The reversal of 20217517 is 71571202.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20217517 - 2¹⁹ = 19693229 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20217491 and 20217500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20217557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1893 + ... + 6634.

It is an arithmetic number, because the mean of its divisors is an integer number (5057104).

Almost surely, 2^20217517 is an apocalyptic number.

It is an amenable number.

20217517 is a deficient number, since it is larger than the sum of its proper divisors (10899).

20217517 is an equidigital number, since it uses as much as digits as its factorization.

20217517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10898.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 20217517 is about 4496.3893292285. The cubic root of 20217517 is about 272.4222688821.

Adding to 20217517 its reverse (71571202), we get a palindrome (91788719).

The spelling of 20217517 in words is "twenty million, two hundred seventeen thousand, five hundred seventeen".