21200020 has 48 divisors (see below), whose sum is σ = 49206528. Its totient is φ = 7631360.

The previous prime is 21199999. The next prime is 21200021. The reversal of 21200020 is 2000212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21199976 and 21200012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6465 + ... + 9175.

It is an arithmetic number, because the mean of its divisors is an integer number (1025136).

Almost surely, 2^21200020 is an apocalyptic number.

21200020 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 21200020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24603264).

21200020 is an abundant number, since it is smaller than the sum of its proper divisors (28006508).

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

21200020 is a wasteful number, since it uses less digits than its factorization.

21200020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2760 (or 2758 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 7.

The square root of 21200020 is about 4604.3479451492. The cubic root of 21200020 is about 276.7655877620.

Adding to 21200020 its reverse (2000212), we get a palindrome (23200232).

The spelling of 21200020 in words is "twenty-one million, two hundred thousand, twenty".