21033420 has 72 divisors (see below), whose sum is σ = 62613264. Its totient is φ = 5274624.

The previous prime is 21033413. The next prime is 21033433. The reversal of 21033420 is 2433012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21033420.

It is an unprimeable number.

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, 16734 + ... + 17946.

Almost surely, 2^21033420 is an apocalyptic number.

21033420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21033420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31306632).

21033420 is an abundant number, since it is smaller than the sum of its proper divisors (41579844).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21033420 is a wasteful number, since it uses less digits than its factorization.

21033420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1259 (or 1240 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21033420 is about 4586.2206663003. The cubic root of 21033420 is about 276.0386944279.

Adding to 21033420 its reverse (2433012), we get a palindrome (23466432).

The spelling of 21033420 in words is "twenty-one million, thirty-three thousand, four hundred twenty".