19919387 has 2 divisors, whose sum is σ = 19919388. Its totient is φ = 19919386.

The previous prime is 19919377. The next prime is 19919401. The reversal of 19919387 is 78391991.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (78391991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19919387 - 2⁶ = 19919323 is a prime.

It is not a weakly prime, because it can be changed into another prime (19919327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9959693 + 9959694.

It is an arithmetic number, because the mean of its divisors is an integer number (9959694).

Almost surely, 2^19919387 is an apocalyptic number.

19919387 is a deficient number, since it is larger than the sum of its proper divisors (1).

19919387 is an equidigital number, since it uses as much as digits as its factorization.

19919387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 47.

The square root of 19919387 is about 4463.1140473889. The cubic root of 19919387 is about 271.0765749937.

The spelling of 19919387 in words is "nineteen million, nine hundred nineteen thousand, three hundred eighty-seven".