21003738 has 64 divisors (see below), whose sum is σ = 53084160. Its totient is φ = 5398272.

The previous prime is 21003727. The next prime is 21003751. The reversal of 21003738 is 83730012.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15783 + ... + 17061.

It is an arithmetic number, because the mean of its divisors is an integer number (829440).

Almost surely, 2^21003738 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21003738, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26542080).

21003738 is an abundant number, since it is smaller than the sum of its proper divisors (32080422).

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

21003738 is a wasteful number, since it uses less digits than its factorization.

21003738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1331.

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21003738 is about 4582.9835260450. The cubic root of 21003738 is about 275.9087862837.

The spelling of 21003738 in words is "twenty-one million, three thousand, seven hundred thirty-eight".