21316636 has 24 divisors (see below), whose sum is σ = 40869360. Its totient is φ = 9648000.

The previous prime is 21316619. The next prime is 21316639. The reversal of 21316636 is 63661312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21316639) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10936 + ... + 12736.

It is an arithmetic number, because the mean of its divisors is an integer number (1702890).

Almost surely, 2^21316636 is an apocalyptic number.

It is an amenable number.

21316636 is a deficient number, since it is larger than the sum of its proper divisors (19552724).

21316636 is a wasteful number, since it uses less digits than its factorization.

21316636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2085 (or 2083 counting only the distinct ones).

The product of its digits is 3888, while the sum is 28.

The square root of 21316636 is about 4616.9942603386. The cubic root of 21316636 is about 277.2721328271.

Adding to 21316636 its reverse (63661312), we get a palindrome (84977948).

It can be divided in two parts, 21316 and 636, that added together give a cube (21952 = 28³).

The spelling of 21316636 in words is "twenty-one million, three hundred sixteen thousand, six hundred thirty-six".