21087003 has 24 divisors (see below), whose sum is σ = 33598992. Its totient is φ = 11721024.

The previous prime is 21086981. The next prime is 21087019. The reversal of 21087003 is 30078012.

It is not a de Polignac number, because 21087003 - 2⁵ = 21086971 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21087023) 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 23 ways as a sum of consecutive naturals, for example, 3501 + ... + 7377.

It is an arithmetic number, because the mean of its divisors is an integer number (1399958).

Almost surely, 2^21087003 is an apocalyptic number.

21087003 is a deficient number, since it is larger than the sum of its proper divisors (12511989).

21087003 is a wasteful number, since it uses less digits than its factorization.

21087003 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3931 (or 3924 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21087003 is about 4592.0586886494. The cubic root of 21087003 is about 276.2729001033.

The spelling of 21087003 in words is "twenty-one million, eighty-seven thousand, three".