21053250 has 64 divisors (see below), whose sum is σ = 58406400. Its totient is φ = 5612400.

The previous prime is 21053203. The next prime is 21053267. The reversal of 21053250 is 5235012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5191 + ... + 8309.

It is an arithmetic number, because the mean of its divisors is an integer number (912600).

Almost surely, 2^21053250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21053250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29203200).

21053250 is an abundant number, since it is smaller than the sum of its proper divisors (37353150).

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

21053250 is a wasteful number, since it uses less digits than its factorization.

21053250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3145 (or 3129 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21053250 is about 4588.3820677882. The cubic root of 21053250 is about 276.1254155918.

Adding to 21053250 its reverse (5235012), we get a palindrome (26288262).

The spelling of 21053250 in words is "twenty-one million, fifty-three thousand, two hundred fifty".