21858400 has 72 divisors (see below), whose sum is σ = 54137160. Its totient is φ = 8616960.

The previous prime is 21858391. The next prime is 21858427. The reversal of 21858400 is 485812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71047 + ... + 71353.

It is an arithmetic number, because the mean of its divisors is an integer number (751905).

Almost surely, 2^21858400 is an apocalyptic number.

21858400 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 21858400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27068580).

21858400 is an abundant number, since it is smaller than the sum of its proper divisors (32278760).

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

21858400 is a wasteful number, since it uses less digits than its factorization.

21858400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416 (or 403 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 21858400 is about 4675.2967820236. The cubic root of 21858400 is about 279.6014738601.

It can be divided in two parts, 2185 and 8400, that added together give a triangular number (10585 = T₁₄₅).

The spelling of 21858400 in words is "twenty-one million, eight hundred fifty-eight thousand, four hundred".