16391809 has 4 divisors (see below), whose sum is σ = 18733504. Its totient is φ = 14050116.

The previous prime is 16391803. The next prime is 16391819. The reversal of 16391809 is 90819361.

16391809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 90819361 = 7127 ⋅12743.

It is a cyclic number.

It is not a de Polignac number, because 16391809 - 2¹⁹ = 15867521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16391803) 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, 1170837 + ... + 1170850.

It is an arithmetic number, because the mean of its divisors is an integer number (4683376).

Almost surely, 2^16391809 is an apocalyptic number.

It is an amenable number.

16391809 is a deficient number, since it is larger than the sum of its proper divisors (2341695).

16391809 is an equidigital number, since it uses as much as digits as its factorization.

16391809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2341694.

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 16391809 is about 4048.6799083158. The cubic root of 16391809 is about 254.0245135165.

The spelling of 16391809 in words is "sixteen million, three hundred ninety-one thousand, eight hundred nine".