21202120 has 64 divisors (see below), whose sum is σ = 49630320. Its totient is φ = 8146944.

The previous prime is 21202079. The next prime is 21202121. The reversal of 21202120 is 2120212.

It can be written as a sum of positive squares in 8 ways, for example, as 13147876 + 8054244 = 3626^2 + 2838^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21202097 and 21202106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202121) 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, 154692 + ... + 154828.

Almost surely, 2^21202120 is an apocalyptic number.

21202120 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 21202120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24815160).

21202120 is an abundant number, since it is smaller than the sum of its proper divisors (28428200).

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

21202120 is a wasteful number, since it uses less digits than its factorization.

21202120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274 (or 270 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21202120 is about 4604.5759848221. The cubic root of 21202120 is about 276.7747259381.

21202120 divided by its sum of digits (10) gives a palindrome (2120212).

Adding to 21202120 its reverse (2120212), we get a palindrome (23322332).

The spelling of 21202120 in words is "twenty-one million, two hundred two thousand, one hundred twenty".