21009033 has 6 divisors (see below), whose sum is σ = 30346394. Its totient is φ = 14006016.

The previous prime is 21009017. The next prime is 21009061. The reversal of 21009033 is 33090012.

It can be written as a sum of positive squares in only one way, i.e., 12027024 + 8982009 = 3468^2 + 2997^2 .

It is not a de Polignac number, because 21009033 - 2⁴ = 21009017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21008997 and 21009015.

It is not an unprimeable number, because it can be changed into a prime (21009533) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1167160 + ... + 1167177.

Almost surely, 2^21009033 is an apocalyptic number.

It is an amenable number.

21009033 is a deficient number, since it is larger than the sum of its proper divisors (9337361).

21009033 is a wasteful number, since it uses less digits than its factorization.

21009033 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2334343 (or 2334340 counting only the distinct ones).

The product of its (nonzero) digits is 162, while the sum is 18.

The square root of 21009033 is about 4583.5611700947. The cubic root of 21009033 is about 275.9319696852.

Adding to 21009033 its reverse (33090012), we get a palindrome (54099045).

The spelling of 21009033 in words is "twenty-one million, nine thousand, thirty-three".