19813909 has 4 divisors (see below), whose sum is σ = 19847916. Its totient is φ = 19779904.

The previous prime is 19813897. The next prime is 19813919. The reversal of 19813909 is 90931891.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16402500 + 3411409 = 4050^2 + 1847^2 .

It is a cyclic number.

It is not a de Polignac number, because 19813909 - 2¹¹ = 19811861 is a prime.

It is a super-3 number, since 3×19813909³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19813919) 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, 16114 + ... + 17299.

It is an arithmetic number, because the mean of its divisors is an integer number (4961979).

Almost surely, 2^19813909 is an apocalyptic number.

It is an amenable number.

19813909 is a deficient number, since it is larger than the sum of its proper divisors (34007).

19813909 is an equidigital number, since it uses as much as digits as its factorization.

19813909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34006.

The product of its (nonzero) digits is 17496, while the sum is 40.

The square root of 19813909 is about 4451.2817255258. The cubic root of 19813909 is about 270.5972558216.

The spelling of 19813909 in words is "nineteen million, eight hundred thirteen thousand, nine hundred nine".