21633020 has 24 divisors (see below), whose sum is σ = 47821200. Its totient is φ = 8197632.

The previous prime is 21633011. The next prime is 21633023. The reversal of 21633020 is 2033612.

It is a self number, because there is not a number n which added to its sum of digits gives 21633020.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21633023) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28085 + ... + 28844.

It is an arithmetic number, because the mean of its divisors is an integer number (1992550).

Almost surely, 2^21633020 is an apocalyptic number.

21633020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21633020 is an abundant number, since it is smaller than the sum of its proper divisors (26188180).

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

21633020 is a wasteful number, since it uses less digits than its factorization.

21633020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56957 (or 56955 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 21633020 is about 4651.1310452405. The cubic root of 21633020 is about 278.6371700450.

Adding to 21633020 its reverse (2033612), we get a palindrome (23666632).

The spelling of 21633020 in words is "twenty-one million, six hundred thirty-three thousand, twenty".