20028509 has 2 divisors, whose sum is σ = 20028510. Its totient is φ = 20028508.

The previous prime is 20028467. The next prime is 20028517. The reversal of 20028509 is 90582002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13853284 + 6175225 = 3722^2 + 2485^2 .

It is a cyclic number.

It is not a de Polignac number, because 20028509 - 2¹⁶ = 19962973 is a prime.

It is a super-2 number, since 2×20028509² = 802282345526162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20028529) 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, 10014254 + 10014255.

It is an arithmetic number, because the mean of its divisors is an integer number (10014255).

Almost surely, 2^20028509 is an apocalyptic number.

It is an amenable number.

20028509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20028509 is an equidigital number, since it uses as much as digits as its factorization.

20028509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 20028509 is about 4475.3222230360. The cubic root of 20028509 is about 271.5706759783.

The spelling of 20028509 in words is "twenty million, twenty-eight thousand, five hundred nine".