21528180 has 120 divisors (see below), whose sum is σ = 68728968. Its totient is φ = 5640192.

The previous prime is 21528173. The next prime is 21528193. The reversal of 21528180 is 8182512.

It can be written as a sum of positive squares in 4 ways, for example, as 2396304 + 19131876 = 1548^2 + 4374^2 .

It is a super-2 number, since 2×21528180² = 926925068224800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 157072 + ... + 157208.

Almost surely, 2^21528180 is an apocalyptic number.

21528180 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 21528180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34364484).

21528180 is an abundant number, since it is smaller than the sum of its proper divisors (47200788).

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

21528180 is a wasteful number, since it uses less digits than its factorization.

21528180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255 (or 244 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 21528180 is about 4639.8469802354. The cubic root of 21528180 is about 278.1863216215.

The spelling of 21528180 in words is "twenty-one million, five hundred twenty-eight thousand, one hundred eighty".