21116 has 6 divisors (see below), whose sum is σ = 36960. Its totient is φ = 10556.

The previous prime is 21107. The next prime is 21121. The reversal of 21116 is 61112.

It is a pancake number, because a pancake can be divided into 21116 parts by 205 straight cuts.

It is a junction number, because it is equal to n+sod(n) for n = 21097 and 21106.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21116.

It is an unprimeable number.

21116 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2636 + ... + 2643.

It is an arithmetic number, because the mean of its divisors is an integer number (6160).

2²¹¹¹⁶ is an apocalyptic number.

It is an amenable number.

21116 is a deficient number, since it is larger than the sum of its proper divisors (15844).

21116 is a wasteful number, since it uses less digits than its factorization.

21116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5283 (or 5281 counting only the distinct ones).

The product of its digits is 12, while the sum is 11.

The square root of 21116 is about 145.3134542979. The cubic root of 21116 is about 27.6399477535.

Adding to 21116 its reverse (61112), we get a palindrome (82228).

The spelling of 21116 in words is "twenty-one thousand, one hundred sixteen".