21113513 has 4 divisors (see below), whose sum is σ = 21162708. Its totient is φ = 21064320.

The previous prime is 21113467. The next prime is 21113527. The reversal of 21113513 is 31531112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12334144 + 8779369 = 3512^2 + 2963^2 .

It is a cyclic number.

It is not a de Polignac number, because 21113513 - 2¹⁴ = 21097129 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21113491 and 21113500.

It is not an unprimeable number, because it can be changed into a prime (21113593) 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, 23948 + ... + 24813.

It is an arithmetic number, because the mean of its divisors is an integer number (5290677).

Almost surely, 2^21113513 is an apocalyptic number.

It is an amenable number.

21113513 is a deficient number, since it is larger than the sum of its proper divisors (49195).

21113513 is an equidigital number, since it uses as much as digits as its factorization.

21113513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49194.

The product of its digits is 90, while the sum is 17.

The square root of 21113513 is about 4594.9442869310. The cubic root of 21113513 is about 276.3886258508.

Adding to 21113513 its reverse (31531112), we get a palindrome (52644625).

The spelling of 21113513 in words is "twenty-one million, one hundred thirteen thousand, five hundred thirteen".