21552500 has 60 divisors (see below), whose sum is σ = 48612564. Its totient is φ = 8352000.

The previous prime is 21552499. The next prime is 21552521. The reversal of 21552500 is 525512.

It can be written as a sum of positive squares in 10 ways, for example, as 15272464 + 6280036 = 3908^2 + 2506^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

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 19 ways as a sum of consecutive naturals, for example, 92384 + ... + 92616.

Almost surely, 2^21552500 is an apocalyptic number.

21552500 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 21552500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24306282).

21552500 is an abundant number, since it is smaller than the sum of its proper divisors (27060064).

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

21552500 is a wasteful number, since it uses less digits than its factorization.

21552500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 294 (or 277 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 20.

The square root of 21552500 is about 4642.4670165764. The cubic root of 21552500 is about 278.2910362378.

The spelling of 21552500 in words is "twenty-one million, five hundred fifty-two thousand, five hundred".