19915009 has 2 divisors, whose sum is σ = 19915010. Its totient is φ = 19915008.

The previous prime is 19915001. The next prime is 19915039. The reversal of 19915009 is 90051991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19891600 + 23409 = 4460^2 + 153^2 .

It is a cyclic number.

It is not a de Polignac number, because 19915009 - 2³ = 19915001 is a prime.

It is not a weakly prime, because it can be changed into another prime (19915001) 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, 9957504 + 9957505.

It is an arithmetic number, because the mean of its divisors is an integer number (9957505).

Almost surely, 2^19915009 is an apocalyptic number.

It is an amenable number.

19915009 is a deficient number, since it is larger than the sum of its proper divisors (1).

19915009 is an equidigital number, since it uses as much as digits as its factorization.

19915009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3645, while the sum is 34.

The square root of 19915009 is about 4462.6235557125. The cubic root of 19915009 is about 271.0567139374.

The spelling of 19915009 in words is "nineteen million, nine hundred fifteen thousand, nine".