21036736 has 28 divisors (see below), whose sum is σ = 47709328. Its totient is φ = 9015552.

The previous prime is 21036721. The next prime is 21036737. The reversal of 21036736 is 63763012.

It is a tau number, because it is divible by the number of its divisors (28).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23031 + ... + 23926.

Almost surely, 2^21036736 is an apocalyptic number.

It is an amenable number.

21036736 is an abundant number, since it is smaller than the sum of its proper divisors (26672592).

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

21036736 is an equidigital number, since it uses as much as digits as its factorization.

21036736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46976 (or 46966 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 28.

The square root of 21036736 is about 4586.5821697643. The cubic root of 21036736 is about 276.0531998548.

Adding to 21036736 its reverse (63763012), we get a palindrome (84799748).

The spelling of 21036736 in words is "twenty-one million, thirty-six thousand, seven hundred thirty-six".