21104636 has 12 divisors (see below), whose sum is σ = 42209328. Its totient is φ = 9044832.

The previous prime is 21104591. The next prime is 21104641. The reversal of 21104636 is 63640112.

It is a happy number.

21104636 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 376841 + ... + 376896.

It is an arithmetic number, because the mean of its divisors is an integer number (3517444).

Almost surely, 2^21104636 is an apocalyptic number.

It is an amenable number.

21104636 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21104636 is a wasteful number, since it uses less digits than its factorization.

21104636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 753748 (or 753746 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21104636 is about 4593.9782324256. The cubic root of 21104636 is about 276.3498853253.

Adding to 21104636 its reverse (63640112), we get a palindrome (84744748).

The spelling of 21104636 in words is "twenty-one million, one hundred four thousand, six hundred thirty-six".