21416 has 8 divisors (see below), whose sum is σ = 40170. Its totient is φ = 10704.

The previous prime is 21407. The next prime is 21419. The reversal of 21416 is 61412.

It can be written as a sum of positive squares in only one way, i.e., 21316 + 100 = 146^2 + 10^2 .

It is a tau number, because it is divible by the number of its divisors (8).

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

It is a nialpdrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 21416.

It is not an unprimeable number, because it can be changed into a prime (21419) by changing a digit.

21416 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 as a sum of consecutive naturals, namely, 1331 + ... + 1346.

2²¹⁴¹⁶ is an apocalyptic number.

It is an amenable number.

21416 is a deficient number, since it is larger than the sum of its proper divisors (18754).

21416 is a wasteful number, since it uses less digits than its factorization.

21416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2683 (or 2679 counting only the distinct ones).

The product of its digits is 48, while the sum is 14.

The square root of 21416 is about 146.3420650394. The cubic root of 21416 is about 27.7702284670.

Adding to 21416 its reverse (61412), we get a palindrome (82828).

The spelling of 21416 in words is "twenty-one thousand, four hundred sixteen".