20861317 has 2 divisors, whose sum is σ = 20861318. Its totient is φ = 20861316.

The previous prime is 20861287. The next prime is 20861327. The reversal of 20861317 is 71316802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13293316 + 7568001 = 3646^2 + 2751^2 .

It is a cyclic number.

It is not a de Polignac number, because 20861317 - 2¹¹ = 20859269 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 (20861327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10430658 + 10430659.

It is an arithmetic number, because the mean of its divisors is an integer number (10430659).

Almost surely, 2^20861317 is an apocalyptic number.

It is an amenable number.

20861317 is a deficient number, since it is larger than the sum of its proper divisors (1).

20861317 is an equidigital number, since it uses as much as digits as its factorization.

20861317 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 20861317 is about 4567.4190742694. The cubic root of 20861317 is about 275.2837489962.

It can be divided in two parts, 2086 and 1317, that added together give a triangular number (3403 = T₈₂).

The spelling of 20861317 in words is "twenty million, eight hundred sixty-one thousand, three hundred seventeen".