21385824 has 48 divisors (see below), whose sum is σ = 56383488. Its totient is φ = 7097472.

The previous prime is 21385823. The next prime is 21385843. The reversal of 21385824 is 42858312.

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 (21385823) 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, 34929 + ... + 35535.

It is an arithmetic number, because the mean of its divisors is an integer number (1174656).

Almost surely, 2^21385824 is an apocalyptic number.

21385824 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21385824 is an abundant number, since it is smaller than the sum of its proper divisors (34997664).

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

21385824 is a wasteful number, since it uses less digits than its factorization.

21385824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 987 (or 979 counting only the distinct ones).

The product of its digits is 15360, while the sum is 33.

The square root of 21385824 is about 4624.4809438466. The cubic root of 21385824 is about 277.5717921547.

The spelling of 21385824 in words is "twenty-one million, three hundred eighty-five thousand, eight hundred twenty-four".