21826 has 8 divisors (see below), whose sum is σ = 37440. Its totient is φ = 9348.

The previous prime is 21821. The next prime is 21839. The reversal of 21826 is 62812.

It is a happy number.

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

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21821) 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, 766 + ... + 793.

It is an arithmetic number, because the mean of its divisors is an integer number (4680).

2²¹⁸²⁶ is an apocalyptic number.

21826 is a deficient number, since it is larger than the sum of its proper divisors (15614).

21826 is a wasteful number, since it uses less digits than its factorization.

21826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1568.

The product of its digits is 192, while the sum is 19.

The square root of 21826 is about 147.7362514754. The cubic root of 21826 is about 27.9463257470.

The spelling of 21826 in words is "twenty-one thousand, eight hundred twenty-six".