21003885 has 48 divisors (see below), whose sum is σ = 42007680. Its totient is φ = 9509760.

The previous prime is 21003883. The next prime is 21003887. The reversal of 21003885 is 58830012.

21003885 = T₁₂₆ + T₁₂₇ + ... + T₅₀₃.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21003883) and next prime (21003887).

It is not a de Polignac number, because 21003885 - 2¹ = 21003883 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003883) 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 47 ways as a sum of consecutive naturals, for example, 41011 + ... + 41519.

It is an arithmetic number, because the mean of its divisors is an integer number (875160).

Almost surely, 2^21003885 is an apocalyptic number.

It is an amenable number.

21003885 is a deficient number, since it is larger than the sum of its proper divisors (21003795).

21003885 is a wasteful number, since it uses less digits than its factorization.

21003885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 658 (or 655 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21003885 is about 4582.9995636046. Note that the first 3 decimals coincide. The cubic root of 21003885 is about 275.9094299548.

Adding to 21003885 its reverse (58830012), we get a palindrome (79833897).

The spelling of 21003885 in words is "twenty-one million, three thousand, eight hundred eighty-five".