20659871 has 2 divisors, whose sum is σ = 20659872. Its totient is φ = 20659870.

The previous prime is 20659867. The next prime is 20659889. The reversal of 20659871 is 17895602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20659871 - 2² = 20659867 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20652871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10329935 + 10329936.

It is an arithmetic number, because the mean of its divisors is an integer number (10329936).

Almost surely, 2^20659871 is an apocalyptic number.

20659871 is a deficient number, since it is larger than the sum of its proper divisors (1).

20659871 is an equidigital number, since it uses as much as digits as its factorization.

20659871 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 20659871 is about 4545.3130805259. The cubic root of 20659871 is about 274.3947946934.

The spelling of 20659871 in words is "twenty million, six hundred fifty-nine thousand, eight hundred seventy-one".