21113 has 4 divisors (see below), whose sum is σ = 21648. Its totient is φ = 20580.

The previous prime is 21107. The next prime is 21121. The reversal of 21113 is 31112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21113 - 2⁸ = 20857 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21113.

It is not an unprimeable number, because it can be changed into a prime (21143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203 + ... + 288.

It is an arithmetic number, because the mean of its divisors is an integer number (5412).

2²¹¹¹³ is an apocalyptic number.

It is an amenable number.

21113 is a deficient number, since it is larger than the sum of its proper divisors (535).

21113 is an equidigital number, since it uses as much as digits as its factorization.

21113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534.

The product of its digits is 6, while the sum is 8.

The square root of 21113 is about 145.3031314184. The cubic root of 21113 is about 27.6386387339.

Adding to 21113 its reverse (31112), we get a palindrome (52225).

Subtracting 21113 from its reverse (31112), we obtain a palindrome (9999).

The spelling of 21113 in words is "twenty-one thousand, one hundred thirteen".