20021717 has 4 divisors (see below), whose sum is σ = 20034636. Its totient is φ = 20008800.

The previous prime is 20021711. The next prime is 20021723. The reversal of 20021717 is 71712002.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (20021711) and next prime (20021723).

It can be written as a sum of positive squares in 2 ways, for example, as 2390116 + 17631601 = 1546^2 + 4199^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20021717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3758 + ... + 7359.

It is an arithmetic number, because the mean of its divisors is an integer number (5008659).

Almost surely, 2^20021717 is an apocalyptic number.

It is an amenable number.

20021717 is a deficient number, since it is larger than the sum of its proper divisors (12919).

20021717 is a wasteful number, since it uses less digits than its factorization.

20021717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12918.

The product of its (nonzero) digits is 196, while the sum is 20.

The square root of 20021717 is about 4474.5633306503. The cubic root of 20021717 is about 271.5399744656.

Adding to 20021717 its reverse (71712002), we get a palindrome (91733719).

The spelling of 20021717 in words is "twenty million, twenty-one thousand, seven hundred seventeen".