21878400 has 192 divisors, whose sum is σ = 75129120. Its totient is φ = 5591040.

The previous prime is 21878369. The next prime is 21878401. The reversal of 21878400 is 487812.

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-4 number, since 4×21878400⁴ (a number of 30 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21878401) 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 23 ways as a sum of consecutive naturals, for example, 412774 + ... + 412826.

Almost surely, 2^21878400 is an apocalyptic number.

21878400 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 21878400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37564560).

21878400 is an abundant number, since it is smaller than the sum of its proper divisors (53250720).

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

21878400 is a wasteful number, since it uses less digits than its factorization.

21878400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 106 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 21878400 is about 4677.4351946339. The cubic root of 21878400 is about 279.6867244551.

The spelling of 21878400 in words is "twenty-one million, eight hundred seventy-eight thousand, four hundred".