21896 has 32 divisors (see below), whose sum is σ = 51840. Its totient is φ = 8448.

The previous prime is 21893. The next prime is 21911. The reversal of 21896 is 69812.

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

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

It is a plaindrome in base 16.

It is a zygodrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21893) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 941 + ... + 963.

It is an arithmetic number, because the mean of its divisors is an integer number (1620).

2²¹⁸⁹⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21896, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25920).

21896 is an abundant number, since it is smaller than the sum of its proper divisors (29944).

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

21896 is a wasteful number, since it uses less digits than its factorization.

21896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53 (or 49 counting only the distinct ones).

The product of its digits is 864, while the sum is 26.

The square root of 21896 is about 147.9729705048. The cubic root of 21896 is about 27.9761702013.

The spelling of 21896 in words is "twenty-one thousand, eight hundred ninety-six".