21518800 has 60 divisors (see below), whose sum is σ = 53969760. Its totient is φ = 8229760.

The previous prime is 21518779. The next prime is 21518803. The reversal of 21518800 is 881512.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518803) 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, 8031 + ... + 10369.

It is an arithmetic number, because the mean of its divisors is an integer number (899496).

Almost surely, 2^21518800 is an apocalyptic number.

21518800 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 21518800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26984880).

21518800 is an abundant number, since it is smaller than the sum of its proper divisors (32450960).

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

21518800 is a wasteful number, since it uses less digits than its factorization.

21518800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2380 (or 2369 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 21518800 is about 4638.8360609101. The cubic root of 21518800 is about 278.1459130847.

The spelling of 21518800 in words is "twenty-one million, five hundred eighteen thousand, eight hundred".