20717217 has 12 divisors (see below), whose sum is σ = 30014244. Its totient is φ = 13770240.

The previous prime is 20717209. The next prime is 20717219. The reversal of 20717217 is 71271702.

It can be written as a sum of positive squares in 2 ways, for example, as 14561856 + 6155361 = 3816^2 + 2481^2 .

It is not a de Polignac number, because 20717217 - 2³ = 20717209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20717219) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 84 + ... + 6437.

It is an arithmetic number, because the mean of its divisors is an integer number (2501187).

Almost surely, 2^20717217 is an apocalyptic number.

It is an amenable number.

20717217 is a deficient number, since it is larger than the sum of its proper divisors (9297027).

20717217 is a wasteful number, since it uses less digits than its factorization.

20717217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6880 (or 6877 counting only the distinct ones).

The product of its (nonzero) digits is 1372, while the sum is 27.

The square root of 20717217 is about 4551.6169654311. The cubic root of 20717217 is about 274.6484411182.

Adding to 20717217 its reverse (71271702), we get a palindrome (91988919).

It can be divided in two parts, 207 and 17217, that added together give a square (17424 = 132²).

The spelling of 20717217 in words is "twenty million, seven hundred seventeen thousand, two hundred seventeen".