21252213 has 20 divisors (see below), whose sum is σ = 32292480. Its totient is φ = 13924872.

The previous prime is 21252211. The next prime is 21252223. The reversal of 21252213 is 31225212.

It is not a de Polignac number, because 21252213 - 2¹ = 21252211 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252211) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2556 + ... + 7002.

It is an arithmetic number, because the mean of its divisors is an integer number (1614624).

Almost surely, 2^21252213 is an apocalyptic number.

It is an amenable number.

21252213 is a deficient number, since it is larger than the sum of its proper divisors (11040267).

21252213 is an equidigital number, since it uses as much as digits as its factorization.

21252213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4518 (or 4509 counting only the distinct ones).

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

The square root of 21252213 is about 4610.0122559490. The cubic root of 21252213 is about 276.9925276128.

Adding to 21252213 its reverse (31225212), we get a palindrome (52477425).

It can be divided in two parts, 212 and 52213, that added together give a palindrome (52425).

The spelling of 21252213 in words is "twenty-one million, two hundred fifty-two thousand, two hundred thirteen".