21004744 has 16 divisors (see below), whose sum is σ = 39438720. Its totient is φ = 10487760.

The previous prime is 21004721. The next prime is 21004771. The reversal of 21004744 is 44740012.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6529 + ... + 9199.

It is an arithmetic number, because the mean of its divisors is an integer number (2464920).

Almost surely, 2^21004744 is an apocalyptic number.

It is an amenable number.

21004744 is a deficient number, since it is larger than the sum of its proper divisors (18433976).

21004744 is a wasteful number, since it uses less digits than its factorization.

21004744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3660 (or 3656 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 21004744 is about 4583.0932785620. The cubic root of 21004744 is about 275.9131912109.

Adding to 21004744 its reverse (44740012), we get a palindrome (65744756).

The spelling of 21004744 in words is "twenty-one million, four thousand, seven hundred forty-four".