21552020 has 48 divisors (see below), whose sum is σ = 52012800. Its totient is φ = 7348224.

The previous prime is 21552007. The next prime is 21552031. The reversal of 21552020 is 2025512.

It is a self number, because there is not a number n which added to its sum of digits gives 21552020.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35681 + ... + 36279.

It is an arithmetic number, because the mean of its divisors is an integer number (1083600).

Almost surely, 2^21552020 is an apocalyptic number.

21552020 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 21552020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26006400).

21552020 is an abundant number, since it is smaller than the sum of its proper divisors (30460780).

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

21552020 is a wasteful number, since it uses less digits than its factorization.

21552020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 872 (or 870 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 21552020 is about 4642.4153196370. The cubic root of 21552020 is about 278.2889702642.

Adding to 21552020 its reverse (2025512), we get a palindrome (23577532).

The spelling of 21552020 in words is "twenty-one million, five hundred fifty-two thousand, twenty".