19809091 has 2 divisors, whose sum is σ = 19809092. Its totient is φ = 19809090.

The previous prime is 19809089. The next prime is 19809107. The reversal of 19809091 is 19090891.

It is a weak prime.

It is an emirp because it is prime and its reverse (19090891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19809091 - 2¹ = 19809089 is a prime.

Together with 19809089, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 19809091.

It is not a weakly prime, because it can be changed into another prime (19809011) 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, 9904545 + 9904546.

It is an arithmetic number, because the mean of its divisors is an integer number (9904546).

Almost surely, 2^19809091 is an apocalyptic number.

19809091 is a deficient number, since it is larger than the sum of its proper divisors (1).

19809091 is an equidigital number, since it uses as much as digits as its factorization.

19809091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 19809091 is about 4450.7405001865. The cubic root of 19809091 is about 270.5753210070.

The spelling of 19809091 in words is "nineteen million, eight hundred nine thousand, ninety-one".