21916 has 6 divisors (see below), whose sum is σ = 38360. Its totient is φ = 10956.

The previous prime is 21911. The next prime is 21929. The reversal of 21916 is 61912.

It is a super-2 number, since 2×21916² = 960622112, which contains 22 as substring.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21893 and 21902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2736 + ... + 2743.

2²¹⁹¹⁶ is an apocalyptic number.

It is an amenable number.

21916 is a deficient number, since it is larger than the sum of its proper divisors (16444).

21916 is a wasteful number, since it uses less digits than its factorization.

21916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5483 (or 5481 counting only the distinct ones).

The product of its digits is 108, while the sum is 19.

The square root of 21916 is about 148.0405349896. The cubic root of 21916 is about 27.9846855029.

It can be divided in two parts, 2191 and 6, that added together give a cube (2197 = 13³).

The spelling of 21916 in words is "twenty-one thousand, nine hundred sixteen".