20659999 has 2 divisors, whose sum is σ = 20660000. Its totient is φ = 20659998.

The previous prime is 20659997. The next prime is 20660047. The reversal of 20659999 is 99995602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20659999 - 2¹ = 20659997 is a prime.

Together with 20659997, it forms a pair of twin primes.

20659999 is a modest number, since divided by 9999 gives 2065 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20659997) 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, 10329999 + 10330000.

It is an arithmetic number, because the mean of its divisors is an integer number (10330000).

Almost surely, 2^20659999 is an apocalyptic number.

20659999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20659999 is an equidigital number, since it uses as much as digits as its factorization.

20659999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 393660, while the sum is 49.

The square root of 20659999 is about 4545.3271609423. The cubic root of 20659999 is about 274.3953613710.

The spelling of 20659999 in words is "twenty million, six hundred fifty-nine thousand, nine hundred ninety-nine".