21724626 has 64 divisors (see below), whose sum is σ = 55157760. Its totient is φ = 5540160.

The previous prime is 21724621. The next prime is 21724649. The reversal of 21724626 is 62642712.

It is a junction number, because it is equal to n+sod(n) for n = 21724593 and 21724602.

It is not an unprimeable number, because it can be changed into a prime (21724621) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26860 + ... + 27656.

It is an arithmetic number, because the mean of its divisors is an integer number (861840).

Almost surely, 2^21724626 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21724626, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27578880).

21724626 is an abundant number, since it is smaller than the sum of its proper divisors (33433134).

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

21724626 is a wasteful number, since it uses less digits than its factorization.

21724626 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 879.

The product of its digits is 8064, while the sum is 30.

The square root of 21724626 is about 4660.9683543230. The cubic root of 21724626 is about 279.0299167570.

The spelling of 21724626 in words is "twenty-one million, seven hundred twenty-four thousand, six hundred twenty-six".