20404 has 6 divisors (see below), whose sum is σ = 35714. Its totient is φ = 10200.

The previous prime is 20399. The next prime is 20407. The reversal of 20404 is 40402.

20404 = T₉₉ + T₁₀₀ + ... + T₁₀₂.

It can be written as a sum of positive squares in only one way, i.e., 10404 + 10000 = 102^2 + 100^2 .

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20407) by changing a digit.

20404 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2547 + ... + 2554.

2²⁰⁴⁰⁴ is an apocalyptic number.

It is an amenable number.

20404 is a deficient number, since it is larger than the sum of its proper divisors (15310).

20404 is a wasteful number, since it uses less digits than its factorization.

20404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5105 (or 5103 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 10.

The square root of 20404 is about 142.8425706854. The cubic root of 20404 is about 27.3257299229.

Adding to 20404 its reverse (40402), we get a palindrome (60806).

It can be divided in two parts, 20 and 404, that added together give a palindrome (424).

The spelling of 20404 in words is "twenty thousand, four hundred four", and thus it is an iban number.