21913824 has 48 divisors (see below), whose sum is σ = 58399488. Its totient is φ = 7193472.

The previous prime is 21913819. The next prime is 21913831. The reversal of 21913824 is 42831912.

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

It is a junction number, because it is equal to n+sod(n) for n = 21913791 and 21913800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4729 + ... + 8135.

It is an arithmetic number, because the mean of its divisors is an integer number (1216656).

Almost surely, 2^21913824 is an apocalyptic number.

21913824 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 21913824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29199744).

21913824 is an abundant number, since it is smaller than the sum of its proper divisors (36485664).

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

21913824 is a wasteful number, since it uses less digits than its factorization.

21913824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3487 (or 3479 counting only the distinct ones).

The product of its digits is 3456, while the sum is 30.

The square root of 21913824 is about 4681.2203537112. The cubic root of 21913824 is about 279.8375928928.

The spelling of 21913824 in words is "twenty-one million, nine hundred thirteen thousand, eight hundred twenty-four".