21113213 has 4 divisors (see below), whose sum is σ = 23032608. Its totient is φ = 19193820.

The previous prime is 21113173. The next prime is 21113221. The reversal of 21113213 is 31231112.

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 21113213 - 2¹² = 21109117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113243) 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, 959681 + ... + 959702.

It is an arithmetic number, because the mean of its divisors is an integer number (5758152).

Almost surely, 2^21113213 is an apocalyptic number.

It is an amenable number.

21113213 is a deficient number, since it is larger than the sum of its proper divisors (1919395).

21113213 is a wasteful number, since it uses less digits than its factorization.

21113213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1919394.

The product of its digits is 36, while the sum is 14.

The square root of 21113213 is about 4594.9116422408. The cubic root of 21113213 is about 276.3873167842.

Adding to 21113213 its reverse (31231112), we get a palindrome (52344325).

The spelling of 21113213 in words is "twenty-one million, one hundred thirteen thousand, two hundred thirteen".