20549509 has 2 divisors, whose sum is σ = 20549510. Its totient is φ = 20549508.

The previous prime is 20549491. The next prime is 20549513. The reversal of 20549509 is 90594502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20052484 + 497025 = 4478^2 + 705^2 .

It is a cyclic number.

It is not a de Polignac number, because 20549509 - 2⁷ = 20549381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20549609) 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, 10274754 + 10274755.

It is an arithmetic number, because the mean of its divisors is an integer number (10274755).

Almost surely, 2^20549509 is an apocalyptic number.

It is an amenable number.

20549509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20549509 is an equidigital number, since it uses as much as digits as its factorization.

20549509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 20549509 is about 4533.1566264580. The cubic root of 20549509 is about 273.9053298601.

The spelling of 20549509 in words is "twenty million, five hundred forty-nine thousand, five hundred nine".