16400009 has 4 divisors (see below), whose sum is σ = 16408704. Its totient is φ = 16391316.

The previous prime is 16399987. The next prime is 16400017. The reversal of 16400009 is 90000461.

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 16400009 - 2⁸ = 16399753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16400309) 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, 197 + ... + 5730.

It is an arithmetic number, because the mean of its divisors is an integer number (4102176).

Almost surely, 2^16400009 is an apocalyptic number.

It is an amenable number.

16400009 is a deficient number, since it is larger than the sum of its proper divisors (8695).

16400009 is an equidigital number, since it uses as much as digits as its factorization.

16400009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8694.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 16400009 is about 4049.6924574590. The cubic root of 16400009 is about 254.0668650301.

The spelling of 16400009 in words is "sixteen million, four hundred thousand, nine".