19890919 has 2 divisors, whose sum is σ = 19890920. Its totient is φ = 19890918.

The previous prime is 19890911. The next prime is 19890961. The reversal of 19890919 is 91909891.

It is a weak prime.

It is an emirp because it is prime and its reverse (91909891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19890919 - 2³ = 19890911 is a prime.

It is a super-4 number, since 4×19890919⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19890911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9945459 + 9945460.

It is an arithmetic number, because the mean of its divisors is an integer number (9945460).

Almost surely, 2^19890919 is an apocalyptic number.

19890919 is a deficient number, since it is larger than the sum of its proper divisors (1).

19890919 is an equidigital number, since it uses as much as digits as its factorization.

19890919 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52488, while the sum is 46.

The square root of 19890919 is about 4459.9236540551. The cubic root of 19890919 is about 270.9473761193.

The spelling of 19890919 in words is "nineteen million, eight hundred ninety thousand, nine hundred nineteen".