16405 has 8 divisors (see below), whose sum is σ = 20952. Its totient is φ = 12288.

The previous prime is 16381. The next prime is 16411. The reversal of 16405 is 50461.

16405 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 1764 + 14641 = 42^2 + 121^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 6-Lehmer number, since φ(16405) divides (16405-1)⁶.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16405 is a prime.

It is a Duffinian number.

16405 is strictly pandigital in base 6.

It is a plaindrome in base 9.

It is a nialpdrome in base 7.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12 + ... + 181.

It is an arithmetic number, because the mean of its divisors is an integer number (2619).

2¹⁶⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

16405 is a deficient number, since it is larger than the sum of its proper divisors (4547).

16405 is a wasteful number, since it uses less digits than its factorization.

16405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 16405 is about 128.0820049812. The cubic root of 16405 is about 25.4092635730.

Adding to 16405 its reverse (50461), we get a palindrome (66866).

The spelling of 16405 in words is "sixteen thousand, four hundred five".