21042384 has 60 divisors (see below), whose sum is σ = 59767008. Its totient is φ = 6374720.

The previous prime is 21042383. The next prime is 21042407. The reversal of 21042384 is 48324012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042383) 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, 3997 + ... + 7619.

Almost surely, 2^21042384 is an apocalyptic number.

21042384 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 21042384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29883504).

21042384 is an abundant number, since it is smaller than the sum of its proper divisors (38724624).

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

21042384 is a wasteful number, since it uses less digits than its factorization.

21042384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3656 (or 3639 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 21042384 is about 4587.1978374603. The cubic root of 21042384 is about 276.0779028151.

Adding to 21042384 its reverse (48324012), we get a palindrome (69366396).

The spelling of 21042384 in words is "twenty-one million, forty-two thousand, three hundred eighty-four".