16404821 has 2 divisors, whose sum is σ = 16404822. Its totient is φ = 16404820.

The previous prime is 16404811. The next prime is 16404841. The reversal of 16404821 is 12840461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12040900 + 4363921 = 3470^2 + 2089^2 .

It is an emirp because it is prime and its reverse (12840461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16404821 - 2⁶ = 16404757 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16404811) 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, 8202410 + 8202411.

It is an arithmetic number, because the mean of its divisors is an integer number (8202411).

Almost surely, 2^16404821 is an apocalyptic number.

It is an amenable number.

16404821 is a deficient number, since it is larger than the sum of its proper divisors (1).

16404821 is an equidigital number, since it uses as much as digits as its factorization.

16404821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 16404821 is about 4050.2865330739. The cubic root of 16404821 is about 254.0917115653.

The spelling of 16404821 in words is "sixteen million, four hundred four thousand, eight hundred twenty-one".