21378144 has 48 divisors (see below), whose sum is σ = 56814912. Its totient is φ = 7037568.

The previous prime is 21378143. The next prime is 21378151. The reversal of 21378144 is 44187312.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21378143) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6627 + ... + 9309.

It is an arithmetic number, because the mean of its divisors is an integer number (1183644).

Almost surely, 2^21378144 is an apocalyptic number.

21378144 is a gapful number since it is divisible by the number (24) 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 21378144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28407456).

21378144 is an abundant number, since it is smaller than the sum of its proper divisors (35436768).

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

21378144 is a wasteful number, since it uses less digits than its factorization.

21378144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2779 (or 2771 counting only the distinct ones).

The product of its digits is 5376, while the sum is 30.

The square root of 21378144 is about 4623.6505058233. The cubic root of 21378144 is about 277.5385613161.

The spelling of 21378144 in words is "twenty-one million, three hundred seventy-eight thousand, one hundred forty-four".