19990609 has 2 divisors, whose sum is σ = 19990610. Its totient is φ = 19990608.

The previous prime is 19990601. The next prime is 19990613. The reversal of 19990609 is 90609991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10870209 + 9120400 = 3297^2 + 3020^2 .

It is a cyclic number.

It is not a de Polignac number, because 19990609 - 2³ = 19990601 is a prime.

It is not a weakly prime, because it can be changed into another prime (19990601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9995304 + 9995305.

It is an arithmetic number, because the mean of its divisors is an integer number (9995305).

Almost surely, 2^19990609 is an apocalyptic number.

It is an amenable number.

19990609 is a deficient number, since it is larger than the sum of its proper divisors (1).

19990609 is an equidigital number, since it uses as much as digits as its factorization.

19990609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39366, while the sum is 43.

The square root of 19990609 is about 4471.0858860013. The cubic root of 19990609 is about 271.3992698484.

The spelling of 19990609 in words is "nineteen million, nine hundred ninety thousand, six hundred nine".