21033005 has 18 divisors (see below), whose sum is σ = 29460906. Its totient is φ = 14373408.

The previous prime is 21032993. The next prime is 21033007. The reversal of 21033005 is 50033012.

It can be written as a sum of positive squares in 3 ways, for example, as 12348196 + 8684809 = 3514^2 + 2947^2 .

It is not a de Polignac number, because 21033005 - 2¹⁸ = 20770861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033007) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 71639 + ... + 71931.

It is an arithmetic number, because the mean of its divisors is an integer number (1636717).

Almost surely, 2^21033005 is an apocalyptic number.

It is an amenable number.

21033005 is a deficient number, since it is larger than the sum of its proper divisors (8427901).

21033005 is an frugal number, since it uses more digits than its factorization.

21033005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 605 (or 305 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 14.

The square root of 21033005 is about 4586.1754218521. The cubic root of 21033005 is about 276.0368789550.

Adding to 21033005 its reverse (50033012), we get a palindrome (71066017).

The spelling of 21033005 in words is "twenty-one million, thirty-three thousand, five".