21025500 has 96 divisors (see below), whose sum is σ = 62270208. Its totient is φ = 5512000.

The previous prime is 21025469. The next prime is 21025507. The reversal of 21025500 is 552012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21025500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21025507) by changing a digit.

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, 160435 + ... + 160565.

It is an arithmetic number, because the mean of its divisors is an integer number (648648).

Almost surely, 2^21025500 is an apocalyptic number.

21025500 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 21025500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31135104).

21025500 is an abundant number, since it is smaller than the sum of its proper divisors (41244708).

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

21025500 is a wasteful number, since it uses less digits than its factorization.

21025500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260 (or 248 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 21025500 is about 4585.3571289486. The cubic root of 21025500 is about 276.0040432090.

Adding to 21025500 its reverse (552012), we get a palindrome (21577512).

The spelling of 21025500 in words is "twenty-one million, twenty-five thousand, five hundred".