20826 has 24 divisors (see below), whose sum is σ = 49140. Its totient is φ = 6336.

The previous prime is 20809. The next prime is 20849. The reversal of 20826 is 62802.

20826 = T₂₅ + T₂₆ + ... + T₅₁.

It can be written as a sum of positive squares in 2 ways, for example, as 18225 + 2601 = 135^2 + 51^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 20799 and 20808.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 190 + ... + 278.

2²⁰⁸²⁶ is an apocalyptic number.

20826 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 20826, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24570).

20826 is an abundant number, since it is smaller than the sum of its proper divisors (28314).

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

20826 is a wasteful number, since it uses less digits than its factorization.

20826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110 (or 107 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 20826 is about 144.3121616497. The cubic root of 20826 is about 27.5128314775.

The spelling of 20826 in words is "twenty thousand, eight hundred twenty-six".