21636113 has 4 divisors (see below), whose sum is σ = 21683508. Its totient is φ = 21588720.

The previous prime is 21636107. The next prime is 21636143. The reversal of 21636113 is 31163612.

It is a happy number.

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 3214849 + 18421264 = 1793^2 + 4292^2 .

It is a cyclic number.

It is not a de Polignac number, because 21636113 - 2⁶ = 21636049 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21636143) 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, 23006 + ... + 23927.

It is an arithmetic number, because the mean of its divisors is an integer number (5420877).

Almost surely, 2^21636113 is an apocalyptic number.

It is an amenable number.

21636113 is a deficient number, since it is larger than the sum of its proper divisors (47395).

21636113 is an equidigital number, since it uses as much as digits as its factorization.

21636113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47394.

The product of its digits is 648, while the sum is 23.

The square root of 21636113 is about 4651.4635331259. The cubic root of 21636113 is about 278.6504488767.

Adding to 21636113 its reverse (31163612), we get a palindrome (52799725).

The spelling of 21636113 in words is "twenty-one million, six hundred thirty-six thousand, one hundred thirteen".