21106 has 8 divisors (see below), whose sum is σ = 32364. Its totient is φ = 10320.

The previous prime is 21101. The next prime is 21107. The reversal of 21106 is 60112.

It can be written as a sum of positive squares in 2 ways, for example, as 21025 + 81 = 145^2 + 9^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21092 and 21101.

It is not an unprimeable number, because it can be changed into a prime (21101) 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, 36 + ... + 208.

2²¹¹⁰⁶ is an apocalyptic number.

21106 is a deficient number, since it is larger than the sum of its proper divisors (11258).

21106 is a wasteful number, since it uses less digits than its factorization.

21106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21106 is about 145.2790418471. The cubic root of 21106 is about 27.6355838727.

Adding to 21106 its reverse (60112), we get a palindrome (81218).

It can be divided in two parts, 2110 and 6, that added together give a square (2116 = 46²).

The spelling of 21106 in words is "twenty-one thousand, one hundred six".