21716 has 12 divisors (see below), whose sum is σ = 39060. Its totient is φ = 10560.

The previous prime is 21713. The next prime is 21727. The reversal of 21716 is 61712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 2116 + 19600 = 46^2 + 140^2 .

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 21694 and 21703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21713) 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 3 ways as a sum of consecutive naturals, for example, 200 + ... + 288.

It is an arithmetic number, because the mean of its divisors is an integer number (3255).

2²¹⁷¹⁶ is an apocalyptic number.

It is an amenable number.

21716 is a deficient number, since it is larger than the sum of its proper divisors (17344).

21716 is a wasteful number, since it uses less digits than its factorization.

21716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154 (or 152 counting only the distinct ones).

The product of its digits is 84, while the sum is 17.

The square root of 21716 is about 147.3634961583. The cubic root of 21716 is about 27.8992981243.

It can be divided in two parts, 21 and 716, that added together give a palindrome (737).

The spelling of 21716 in words is "twenty-one thousand, seven hundred sixteen".