21033321 has 16 divisors (see below), whose sum is σ = 28993536. Its totient is φ = 13554576.

The previous prime is 21033319. The next prime is 21033329. The reversal of 21033321 is 12333012.

It is not a de Polignac number, because 21033321 - 2¹ = 21033319 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21033321.

It is not an unprimeable number, because it can be changed into a prime (21033329) 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 15 ways as a sum of consecutive naturals, for example, 12496 + ... + 14078.

It is an arithmetic number, because the mean of its divisors is an integer number (1812096).

Almost surely, 2^21033321 is an apocalyptic number.

It is an amenable number.

21033321 is a deficient number, since it is larger than the sum of its proper divisors (7960215).

21033321 is a wasteful number, since it uses less digits than its factorization.

21033321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1732.

The product of its (nonzero) digits is 108, while the sum is 15.

The square root of 21033321 is about 4586.2098730869. The cubic root of 21033321 is about 276.0382613413.

Adding to 21033321 its reverse (12333012), we get a palindrome (33366333).

The spelling of 21033321 in words is "twenty-one million, thirty-three thousand, three hundred twenty-one".