21876 has 12 divisors (see below), whose sum is σ = 51072. Its totient is φ = 7288.

The previous prime is 21871. The next prime is 21881. The reversal of 21876 is 67812.

It is an interprime number because it is at equal distance from previous prime (21871) and next prime (21881).

It is a tau number, because it is divible by the number of its divisors (12).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21871) by changing a digit.

21876 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 in 3 ways as a sum of consecutive naturals, for example, 900 + ... + 923.

It is an arithmetic number, because the mean of its divisors is an integer number (4256).

2²¹⁸⁷⁶ is an apocalyptic number.

It is an amenable number.

21876 is an abundant number, since it is smaller than the sum of its proper divisors (29196).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25536).

21876 is a wasteful number, since it uses less digits than its factorization.

21876 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1830 (or 1828 counting only the distinct ones).

The product of its digits is 672, while the sum is 24.

The square root of 21876 is about 147.9053751559. The cubic root of 21876 is about 27.9676497128.

The spelling of 21876 in words is "twenty-one thousand, eight hundred seventy-six".