21530800 has 60 divisors (see below), whose sum is σ = 54469480. Its totient is φ = 8156160.

The previous prime is 21530797. The next prime is 21530801. The reversal of 21530800 is 803512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (21530801) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6184 + ... + 9016.

Almost surely, 2^21530800 is an apocalyptic number.

21530800 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 21530800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27234740).

21530800 is an abundant number, since it is smaller than the sum of its proper divisors (32938680).

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

21530800 is a wasteful number, since it uses less digits than its factorization.

21530800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2870 (or 2859 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21530800 is about 4640.1293085430. The cubic root of 21530800 is about 278.1976063438.

The spelling of 21530800 in words is "twenty-one million, five hundred thirty thousand, eight hundred".