21033351 has 24 divisors (see below), whose sum is σ = 31855824. Its totient is φ = 13867200.

The previous prime is 21033347. The next prime is 21033367. The reversal of 21033351 is 15333012.

It is not a de Polignac number, because 21033351 - 2² = 21033347 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033371) 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, 24115 + ... + 24971.

It is an arithmetic number, because the mean of its divisors is an integer number (1327326).

Almost surely, 2^21033351 is an apocalyptic number.

21033351 is a deficient number, since it is larger than the sum of its proper divisors (10822473).

21033351 is an equidigital number, since it uses as much as digits as its factorization.

21033351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973 (or 961 counting only the distinct ones).

The product of its (nonzero) digits is 270, while the sum is 18.

The square root of 21033351 is about 4586.2131437603. The cubic root of 21033351 is about 276.0383925798.

Adding to 21033351 its reverse (15333012), we get a palindrome (36366363).

The spelling of 21033351 in words is "twenty-one million, thirty-three thousand, three hundred fifty-one".