20687717 has 2 divisors, whose sum is σ = 20687718. Its totient is φ = 20687716.

The previous prime is 20687707. The next prime is 20687743. The reversal of 20687717 is 71778602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18395521 + 2292196 = 4289^2 + 1514^2 .

It is a cyclic number.

It is not a de Polignac number, because 20687717 - 2⁸ = 20687461 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20687707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10343858 + 10343859.

It is an arithmetic number, because the mean of its divisors is an integer number (10343859).

Almost surely, 2^20687717 is an apocalyptic number.

It is an amenable number.

20687717 is a deficient number, since it is larger than the sum of its proper divisors (1).

20687717 is an equidigital number, since it uses as much as digits as its factorization.

20687717 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32928, while the sum is 38.

The square root of 20687717 is about 4548.3752043999. The cubic root of 20687717 is about 274.5180185539.

The spelling of 20687717 in words is "twenty million, six hundred eighty-seven thousand, seven hundred seventeen".