21158800 has 90 divisors (see below), whose sum is σ = 55220982. Its totient is φ = 7787520.

The previous prime is 21158773. The next prime is 21158803. The reversal of 21158800 is 885112.

It can be written as a sum of positive squares in 9 ways, for example, as 19395216 + 1763584 = 4404^2 + 1328^2 .

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 (21158803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 67444 + ... + 67756.

Almost surely, 2^21158800 is an apocalyptic number.

21158800 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 21158800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27610491).

21158800 is an abundant number, since it is smaller than the sum of its proper divisors (34062182).

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

21158800 is a wasteful number, since it uses less digits than its factorization.

21158800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 357 (or 333 counting only the distinct ones).

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

The square root of 21158800 is about 4599.8695633681. The cubic root of 21158800 is about 276.5860961173.

The spelling of 21158800 in words is "twenty-one million, one hundred fifty-eight thousand, eight hundred".