16405409 has 2 divisors, whose sum is σ = 16405410. Its totient is φ = 16405408.

The previous prime is 16405381. The next prime is 16405421. The reversal of 16405409 is 90450461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16224784 + 180625 = 4028^2 + 425^2 .

It is an emirp because it is prime and its reverse (90450461) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16405409 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (16405429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8202704 + 8202705.

It is an arithmetic number, because the mean of its divisors is an integer number (8202705).

Almost surely, 2^16405409 is an apocalyptic number.

It is an amenable number.

16405409 is a deficient number, since it is larger than the sum of its proper divisors (1).

16405409 is an equidigital number, since it uses as much as digits as its factorization.

16405409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 16405409 is about 4050.3591198806. The cubic root of 16405409 is about 254.0947473424.

The spelling of 16405409 in words is "sixteen million, four hundred five thousand, four hundred nine".