21834 has 12 divisors (see below), whose sum is σ = 47346. Its totient is φ = 7272.

The previous prime is 21821. The next prime is 21839. The reversal of 21834 is 43812.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21609 + 225 = 147^2 + 15^2 .

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1213 = 21834 / (2 + 1 + 8 + 3 + 4).

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21839) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 589 + ... + 624.

2²¹⁸³⁴ is an apocalyptic number.

21834 is an abundant number, since it is smaller than the sum of its proper divisors (25512).

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

21834 is a wasteful number, since it uses less digits than its factorization.

21834 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1221 (or 1218 counting only the distinct ones).

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

The square root of 21834 is about 147.7633242723. The cubic root of 21834 is about 27.9497397684.

It can be divided in two parts, 2183 and 4, that added together give a 7-th power (2187 = 3⁷).

The spelling of 21834 in words is "twenty-one thousand, eight hundred thirty-four".