21202020 has 192 divisors, whose sum is σ = 77414400. Its totient is φ = 4717440.

The previous prime is 21202003. The next prime is 21202033. The reversal of 21202020 is 2020212.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21201993 and 21202011.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 268341 + ... + 268419.

It is an arithmetic number, because the mean of its divisors is an integer number (403200).

Almost surely, 2^21202020 is an apocalyptic number.

21202020 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 21202020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38707200).

21202020 is an abundant number, since it is smaller than the sum of its proper divisors (56212380).

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

21202020 is a wasteful number, since it uses less digits than its factorization.

21202020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 21202020 is about 4604.5651260461. The cubic root of 21202020 is about 276.7742908005.

Adding to 21202020 its reverse (2020212), we get a palindrome (23222232).

The spelling of 21202020 in words is "twenty-one million, two hundred two thousand, twenty".