21003706 has 16 divisors (see below), whose sum is σ = 32117184. Its totient is φ = 10299744.

The previous prime is 21003677. The next prime is 21003707. The reversal of 21003706 is 60730012.

It is not an unprimeable number, because it can be changed into a prime (21003707) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 38125 + ... + 38671.

It is an arithmetic number, because the mean of its divisors is an integer number (2007324).

Almost surely, 2^21003706 is an apocalyptic number.

21003706 is a deficient number, since it is larger than the sum of its proper divisors (11113478).

21003706 is a wasteful number, since it uses less digits than its factorization.

21003706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 885.

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 21003706 is about 4582.9800348681. The cubic root of 21003706 is about 275.9086461644.

Adding to 21003706 its reverse (60730012), we get a palindrome (81733718).

The spelling of 21003706 in words is "twenty-one million, three thousand, seven hundred six".