21355500 has 96 divisors (see below), whose sum is σ = 64995840. Its totient is φ = 5438400.

The previous prime is 21355483. The next prime is 21355501. The reversal of 21355500 is 555312.

It is not an unprimeable number, because it can be changed into a prime (21355501) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34191 + ... + 34809.

It is an arithmetic number, because the mean of its divisors is an integer number (677040).

Almost surely, 2^21355500 is an apocalyptic number.

21355500 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 21355500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32497920).

21355500 is an abundant number, since it is smaller than the sum of its proper divisors (43640340).

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

21355500 is a wasteful number, since it uses less digits than its factorization.

21355500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 664 (or 652 counting only the distinct ones).

The product of its (nonzero) digits is 750, while the sum is 21.

The square root of 21355500 is about 4621.2011425602. The cubic root of 21355500 is about 277.4405359154.

The spelling of 21355500 in words is "twenty-one million, three hundred fifty-five thousand, five hundred".