19999387 has 2 divisors, whose sum is σ = 19999388. Its totient is φ = 19999386.

The previous prime is 19999379. The next prime is 19999411. The reversal of 19999387 is 78399991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19999387 - 2³ = 19999379 is a prime.

It is not a weakly prime, because it can be changed into another prime (19999307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9999693 + 9999694.

It is an arithmetic number, because the mean of its divisors is an integer number (9999694).

Almost surely, 2^19999387 is an apocalyptic number.

19999387 is a deficient number, since it is larger than the sum of its proper divisors (1).

19999387 is an equidigital number, since it uses as much as digits as its factorization.

19999387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1102248, while the sum is 55.

The square root of 19999387 is about 4472.0674189909. The cubic root of 19999387 is about 271.4389884012.

The spelling of 19999387 in words is "nineteen million, nine hundred ninety-nine thousand, three hundred eighty-seven".