19941809 has 4 divisors (see below), whose sum is σ = 20405616. Its totient is φ = 19478004.

The previous prime is 19941791. The next prime is 19941839. The reversal of 19941809 is 90814991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19941809 - 2⁸ = 19941553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19941839) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 231839 + ... + 231924.

It is an arithmetic number, because the mean of its divisors is an integer number (5101404).

Almost surely, 2^19941809 is an apocalyptic number.

It is an amenable number.

19941809 is a deficient number, since it is larger than the sum of its proper divisors (463807).

19941809 is an equidigital number, since it uses as much as digits as its factorization.

19941809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 463806.

The product of its (nonzero) digits is 23328, while the sum is 41.

The square root of 19941809 is about 4465.6252641707. The cubic root of 19941809 is about 271.1782481329.

The spelling of 19941809 in words is "nineteen million, nine hundred forty-one thousand, eight hundred nine".