20006509 has 2 divisors, whose sum is σ = 20006510. Its totient is φ = 20006508.

The previous prime is 20006507. The next prime is 20006531. The reversal of 20006509 is 90560002.

It is an a-pointer prime, because the next prime (20006531) can be obtained adding 20006509 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15824484 + 4182025 = 3978^2 + 2045^2 .

It is a cyclic number.

It is not a de Polignac number, because 20006509 - 2¹ = 20006507 is a prime.

Together with 20006507, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20006509.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20006507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10003254 + 10003255.

It is an arithmetic number, because the mean of its divisors is an integer number (10003255).

Almost surely, 2^20006509 is an apocalyptic number.

It is an amenable number.

20006509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20006509 is an equidigital number, since it uses as much as digits as its factorization.

20006509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 20006509 is about 4472.8636241227. The cubic root of 20006509 is about 271.4712053727.

The spelling of 20006509 in words is "twenty million, six thousand, five hundred nine".