16405504 has 44 divisors (see below), whose sum is σ = 33759124. Its totient is φ = 7962624.

The previous prime is 16405483. The next prime is 16405507. The reversal of 16405504 is 40550461.

It can be written as a sum of positive squares in 2 ways, for example, as 8294400 + 8111104 = 2880^2 + 2848^2 .

It is a super-2 number, since 2×16405504² = 538281122988032, which contains 22 as substring.

It is a nialpdrome in base 4 and base 16.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16405507) 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, 37672 + ... + 38104.

Almost surely, 2^16405504 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 16405504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16879562).

16405504 is an abundant number, since it is smaller than the sum of its proper divisors (17353620).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16405504 is an equidigital number, since it uses as much as digits as its factorization.

16405504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 490 (or 472 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 16405504 is about 4050.3708472188. The cubic root of 16405504 is about 254.0952378098.

Adding to 16405504 its reverse (40550461), we get a palindrome (56955965).

The spelling of 16405504 in words is "sixteen million, four hundred five thousand, five hundred four".