21276 has 24 divisors (see below), whose sum is σ = 55440. Its totient is φ = 7056.

The previous prime is 21269. The next prime is 21277. The reversal of 21276 is 67212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

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

21276 is an undulating number in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21277) 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 7 ways as a sum of consecutive naturals, for example, 10 + ... + 206.

It is an arithmetic number, because the mean of its divisors is an integer number (2310).

2²¹²⁷⁶ 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 21276, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27720).

21276 is an abundant number, since it is smaller than the sum of its proper divisors (34164).

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

21276 is a wasteful number, since it uses less digits than its factorization.

21276 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210 (or 202 counting only the distinct ones).

The product of its digits is 168, while the sum is 18.

The square root of 21276 is about 145.8629493737. The cubic root of 21276 is about 27.7095832377.

Adding to 21276 its reverse (67212), we get a palindrome (88488).

It can be divided in two parts, 2 and 1276, that multiplied together give a palindrome (2552).

The spelling of 21276 in words is "twenty-one thousand, two hundred seventy-six".