21215113 has 4 divisors (see below), whose sum is σ = 21264768. Its totient is φ = 21165460.

The previous prime is 21215111. The next prime is 21215137. The reversal of 21215113 is 31151212.

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 21215113 - 2¹ = 21215111 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21215111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24181 + ... + 25042.

It is an arithmetic number, because the mean of its divisors is an integer number (5316192).

Almost surely, 2^21215113 is an apocalyptic number.

It is an amenable number.

21215113 is a deficient number, since it is larger than the sum of its proper divisors (49655).

21215113 is an equidigital number, since it uses as much as digits as its factorization.

21215113 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49654.

The product of its digits is 60, while the sum is 16.

The square root of 21215113 is about 4605.9866478313. The cubic root of 21215113 is about 276.8312517269.

Adding to 21215113 its reverse (31151212), we get a palindrome (52366325).

The spelling of 21215113 in words is "twenty-one million, two hundred fifteen thousand, one hundred thirteen".