21135663 has 12 divisors (see below), whose sum is σ = 30663360. Its totient is φ = 14028576.

The previous prime is 21135649. The next prime is 21135677. The reversal of 21135663 is 36653112.

It is an interprime number because it is at equal distance from previous prime (21135649) and next prime (21135677).

It is not a de Polignac number, because 21135663 - 2⁹ = 21135151 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135613) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2943 + ... + 7136.

It is an arithmetic number, because the mean of its divisors is an integer number (2555280).

Almost surely, 2^21135663 is an apocalyptic number.

21135663 is a deficient number, since it is larger than the sum of its proper divisors (9527697).

21135663 is a wasteful number, since it uses less digits than its factorization.

21135663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10318 (or 10315 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 21135663 is about 4597.3539128503. The cubic root of 21135663 is about 276.4852443601.

Adding to 21135663 its reverse (36653112), we get a palindrome (57788775).

It can be divided in two parts, 2113 and 5663, that added together give a 5-th power (7776 = 6⁵).

The spelling of 21135663 in words is "twenty-one million, one hundred thirty-five thousand, six hundred sixty-three".