21682724 has 48 divisors (see below), whose sum is σ = 46569600. Its totient is φ = 8626176.

The previous prime is 21682709. The next prime is 21682757. The reversal of 21682724 is 42728612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27812 + ... + 28580.

It is an arithmetic number, because the mean of its divisors is an integer number (970200).

Almost surely, 2^21682724 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 21682724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23284800).

21682724 is an abundant number, since it is smaller than the sum of its proper divisors (24886876).

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

21682724 is a wasteful number, since it uses less digits than its factorization.

21682724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 852 (or 850 counting only the distinct ones).

The product of its digits is 10752, while the sum is 32.

The square root of 21682724 is about 4656.4711960883. The cubic root of 21682724 is about 278.8504056241.

The spelling of 21682724 in words is "twenty-one million, six hundred eighty-two thousand, seven hundred twenty-four".