19123891 has 2 divisors, whose sum is σ = 19123892. Its totient is φ = 19123890.

The previous prime is 19123889. The next prime is 19123903. The reversal of 19123891 is 19832191.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19123891 - 2¹ = 19123889 is a prime.

Together with 19123889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (19123801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9561945 + 9561946.

It is an arithmetic number, because the mean of its divisors is an integer number (9561946).

Almost surely, 2^19123891 is an apocalyptic number.

19123891 is a deficient number, since it is larger than the sum of its proper divisors (1).

19123891 is an equidigital number, since it uses as much as digits as its factorization.

19123891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 34.

The square root of 19123891 is about 4373.0871246752. The cubic root of 19123891 is about 267.4188929288.

The spelling of 19123891 in words is "nineteen million, one hundred twenty-three thousand, eight hundred ninety-one".