21133636 has 6 divisors (see below), whose sum is σ = 36983870. Its totient is φ = 10566816.

The previous prime is 21133631. The next prime is 21133639. The reversal of 21133636 is 63633112.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 65536 = 4590^2 + 256^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21133636.

It is not an unprimeable number, because it can be changed into a prime (21133631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2641701 + ... + 2641708.

Almost surely, 2^21133636 is an apocalyptic number.

It is an amenable number.

21133636 is a deficient number, since it is larger than the sum of its proper divisors (15850234).

21133636 is a wasteful number, since it uses less digits than its factorization.

21133636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5283413 (or 5283411 counting only the distinct ones).

The product of its digits is 1944, while the sum is 25.

The square root of 21133636 is about 4597.1334546650. The cubic root of 21133636 is about 276.4764053738.

Adding to 21133636 its reverse (63633112), we get a palindrome (84766748).

The spelling of 21133636 in words is "twenty-one million, one hundred thirty-three thousand, six hundred thirty-six".