19090909021 has 2 divisors, whose sum is σ = 19090909022. Its totient is φ = 19090909020.

The previous prime is 19090908989. The next prime is 19090909093. The reversal of 19090909021 is 12090909091.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14788992100 + 4301916921 = 121610^2 + 65589^2 .

It is an emirp because it is prime and its reverse (12090909091) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19090909021 - 2⁵ = 19090908989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19090909421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9545454510 + 9545454511.

It is an arithmetic number, because the mean of its divisors is an integer number (9545454511).

Almost surely, 2^19090909021 is an apocalyptic number.

It is an amenable number.

19090909021 is a deficient number, since it is larger than the sum of its proper divisors (1).

19090909021 is an equidigital number, since it uses as much as digits as its factorization.

19090909021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13122, while the sum is 40.

The spelling of 19090909021 in words is "nineteen billion, ninety million, nine hundred nine thousand, twenty-one".