21045213 has 24 divisors (see below), whose sum is σ = 35942400. Its totient is φ = 11610144.

The previous prime is 21045197. The next prime is 21045229. The reversal of 21045213 is 31254012.

21045213 is a `hidden beast` number, since 210 + 452 + 1 + 3 = 666.

It is an interprime number because it is at equal distance from previous prime (21045197) and next prime (21045229).

It is not a de Polignac number, because 21045213 - 2⁴ = 21045197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045263) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3933 + ... + 7586.

It is an arithmetic number, because the mean of its divisors is an integer number (1497600).

Almost surely, 2^21045213 is an apocalyptic number.

It is an amenable number.

21045213 is a deficient number, since it is larger than the sum of its proper divisors (14897187).

21045213 is a wasteful number, since it uses less digits than its factorization.

21045213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11561 (or 11558 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21045213 is about 4587.5061852819. The cubic root of 21045213 is about 276.0902745024.

Adding to 21045213 its reverse (31254012), we get a palindrome (52299225).

The spelling of 21045213 in words is "twenty-one million, forty-five thousand, two hundred thirteen".