21854 has 12 divisors (see below), whose sum is σ = 38304. Its totient is φ = 9324.

The previous prime is 21851. The next prime is 21859. The reversal of 21854 is 45812.

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

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14 + ... + 209.

It is an arithmetic number, because the mean of its divisors is an integer number (3192).

2²¹⁸⁵⁴ is an apocalyptic number.

21854 is a deficient number, since it is larger than the sum of its proper divisors (16450).

21854 is a wasteful number, since it uses less digits than its factorization.

21854 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239 (or 232 counting only the distinct ones).

The product of its digits is 320, while the sum is 20.

The square root of 21854 is about 147.8309845736. The cubic root of 21854 is about 27.9582711751.

It can be divided in two parts, 218 and 54, that added together give a palindrome (272).

The spelling of 21854 in words is "twenty-one thousand, eight hundred fifty-four".