21221300 has 36 divisors (see below), whose sum is σ = 46416300. Its totient is φ = 8421120.

The previous prime is 21221293. The next prime is 21221303. The reversal of 21221300 is 312212.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 682276 + 20539024 = 826^2 + 4532^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221303) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12926 + ... + 14474.

Almost surely, 2^21221300 is an apocalyptic number.

21221300 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 21221300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23208150).

21221300 is an abundant number, since it is smaller than the sum of its proper divisors (25195000).

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

21221300 is a wasteful number, since it uses less digits than its factorization.

21221300 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1700 (or 1693 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21221300 is about 4606.6582247872. The cubic root of 21221300 is about 276.8581600365.

Adding to 21221300 its reverse (312212), we get a palindrome (21533512).

It can be divided in two parts, 212 and 21300, that added together give a palindrome (21512).

The spelling of 21221300 in words is "twenty-one million, two hundred twenty-one thousand, three hundred".