20519209 has 2 divisors, whose sum is σ = 20519210. Its totient is φ = 20519208.

The previous prime is 20519203. The next prime is 20519249. The reversal of 20519209 is 90291502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19607184 + 912025 = 4428^2 + 955^2 .

It is a cyclic number.

It is not a de Polignac number, because 20519209 - 2¹³ = 20511017 is a prime.

It is not a weakly prime, because it can be changed into another prime (20519203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10259604 + 10259605.

It is an arithmetic number, because the mean of its divisors is an integer number (10259605).

Almost surely, 2^20519209 is an apocalyptic number.

It is an amenable number.

20519209 is a deficient number, since it is larger than the sum of its proper divisors (1).

20519209 is an equidigital number, since it uses as much as digits as its factorization.

20519209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 20519209 is about 4529.8133515632. The cubic root of 20519209 is about 273.7706402847.

The spelling of 20519209 in words is "twenty million, five hundred nineteen thousand, two hundred nine".