20686871 has 2 divisors, whose sum is σ = 20686872. Its totient is φ = 20686870.

The previous prime is 20686847. The next prime is 20686873. The reversal of 20686871 is 17868602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20686871 - 2¹⁸ = 20424727 is a prime.

Together with 20686873, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20686873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10343435 + 10343436.

It is an arithmetic number, because the mean of its divisors is an integer number (10343436).

Almost surely, 2^20686871 is an apocalyptic number.

20686871 is a deficient number, since it is larger than the sum of its proper divisors (1).

20686871 is an equidigital number, since it uses as much as digits as its factorization.

20686871 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 20686871 is about 4548.2822032060. The cubic root of 20686871 is about 274.5142764718.

The spelling of 20686871 in words is "twenty million, six hundred eighty-six thousand, eight hundred seventy-one".