21329724 has 48 divisors (see below), whose sum is σ = 54360992. Its totient is φ = 6469632.

The previous prime is 21329719. The next prime is 21329773. The reversal of 21329724 is 42792312.

It is a junction number, because it is equal to n+sod(n) for n = 21329691 and 21329700.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10452 + ... + 12324.

Almost surely, 2^21329724 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21329724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27180496).

21329724 is an abundant number, since it is smaller than the sum of its proper divisors (33031268).

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

21329724 is a wasteful number, since it uses less digits than its factorization.

21329724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1966 (or 1964 counting only the distinct ones).

The product of its digits is 6048, while the sum is 30.

The square root of 21329724 is about 4618.4114151946. The cubic root of 21329724 is about 277.3288677833.

The spelling of 21329724 in words is "twenty-one million, three hundred twenty-nine thousand, seven hundred twenty-four".