21091203 has 48 divisors (see below), whose sum is σ = 37739520. Its totient is φ = 11075328.

The previous prime is 21091201. The next prime is 21091249. The reversal of 21091203 is 30219012.

It is a happy number.

It is not a de Polignac number, because 21091203 - 2¹ = 21091201 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21091201) 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 47 ways as a sum of consecutive naturals, for example, 50128 + ... + 50546.

It is an arithmetic number, because the mean of its divisors is an integer number (786240).

Almost surely, 2^21091203 is an apocalyptic number.

21091203 is a deficient number, since it is larger than the sum of its proper divisors (16648317).

21091203 is a wasteful number, since it uses less digits than its factorization.

21091203 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 496 (or 493 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 21091203 is about 4592.5159771088. The cubic root of 21091203 is about 276.2912410873.

The spelling of 21091203 in words is "twenty-one million, ninety-one thousand, two hundred three".