21238903 has 16 divisors (see below), whose sum is σ = 26080000. Its totient is φ = 17241336.

The previous prime is 21238901. The next prime is 21238939. The reversal of 21238903 is 30983212.

21238903 is a nontrivial binomial coefficient, being equal to C(6518, 2).

It is not a de Polignac number, because 21238903 - 2¹ = 21238901 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21238901) 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 15 ways as a sum of consecutive naturals, for example, 4888 + ... + 8146.

It is an arithmetic number, because the mean of its divisors is an integer number (1630000).

Almost surely, 2^21238903 is an apocalyptic number.

21238903 is the 6517-th triangular number and also the 3259-th hexagonal number.

21238903 is the 2173-rd centered nonagonal number.

21238903 is a deficient number, since it is larger than the sum of its proper divisors (4841097).

21238903 is an equidigital number, since it uses as much as digits as its factorization.

21238903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3299 (or 3285 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21238903 is about 4608.5684328216. The cubic root of 21238903 is about 276.9346898640.

It can be divided in two parts, 2123 and 8903, that added together give a triangular number (11026 = T₁₄₈).

The spelling of 21238903 in words is "twenty-one million, two hundred thirty-eight thousand, nine hundred three".