19722809 has 2 divisors, whose sum is σ = 19722810. Its totient is φ = 19722808.

The previous prime is 19722793. The next prime is 19722823. The reversal of 19722809 is 90822791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19386409 + 336400 = 4403^2 + 580^2 .

It is a cyclic number.

It is not a de Polignac number, because 19722809 - 2⁴ = 19722793 is a prime.

It is not a weakly prime, because it can be changed into another prime (19721809) 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, 9861404 + 9861405.

It is an arithmetic number, because the mean of its divisors is an integer number (9861405).

Almost surely, 2^19722809 is an apocalyptic number.

It is an amenable number.

19722809 is a deficient number, since it is larger than the sum of its proper divisors (1).

19722809 is an equidigital number, since it uses as much as digits as its factorization.

19722809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 19722809 is about 4441.0369284661. The cubic root of 19722809 is about 270.1819030275.

The spelling of 19722809 in words is "nineteen million, seven hundred twenty-two thousand, eight hundred nine".