20985617 has 2 divisors, whose sum is σ = 20985618. Its totient is φ = 20985616.

The previous prime is 20985593. The next prime is 20985649. The reversal of 20985617 is 71658902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20394256 + 591361 = 4516^2 + 769^2 .

It is a cyclic number.

It is not a de Polignac number, because 20985617 - 2¹⁸ = 20723473 is a prime.

It is a super-2 number, since 2×20985617² = 880792241741378, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20985017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10492808 + 10492809.

It is an arithmetic number, because the mean of its divisors is an integer number (10492809).

Almost surely, 2^20985617 is an apocalyptic number.

It is an amenable number.

20985617 is a deficient number, since it is larger than the sum of its proper divisors (1).

20985617 is an equidigital number, since it uses as much as digits as its factorization.

20985617 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 20985617 is about 4581.0061121985. The cubic root of 20985617 is about 275.8294165758.

The spelling of 20985617 in words is "twenty million, nine hundred eighty-five thousand, six hundred seventeen".