21105213 has 8 divisors (see below), whose sum is σ = 28183776. Its totient is φ = 14048400.

The previous prime is 21105199. The next prime is 21105221. The reversal of 21105213 is 31250112.

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

It is not a de Polignac number, because 21105213 - 2⁴ = 21105197 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21105192 and 21105201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105233) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3018 + ... + 7163.

It is an arithmetic number, because the mean of its divisors is an integer number (3522972).

Almost surely, 2^21105213 is an apocalyptic number.

It is an amenable number.

21105213 is a deficient number, since it is larger than the sum of its proper divisors (7078563).

21105213 is a wasteful number, since it uses less digits than its factorization.

21105213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10875.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21105213 is about 4594.0410315973. The cubic root of 21105213 is about 276.3524037677.

Adding to 21105213 its reverse (31250112), we get a palindrome (52355325).

The spelling of 21105213 in words is "twenty-one million, one hundred five thousand, two hundred thirteen".