21723450 has 96 divisors (see below), whose sum is σ = 65245824. Its totient is φ = 4669440.

The previous prime is 21723419. The next prime is 21723451. The reversal of 21723450 is 5432712.

It is a zygodrome in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 21723450.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21723451) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 17242 + ... + 18458.

It is an arithmetic number, because the mean of its divisors is an integer number (679644).

Almost surely, 2^21723450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21723450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32622912).

21723450 is an abundant number, since it is smaller than the sum of its proper divisors (43522374).

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

21723450 is a wasteful number, since it uses less digits than its factorization.

21723450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1256 (or 1251 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 21723450 is about 4660.8421985731. The cubic root of 21723450 is about 279.0248818394.

The spelling of 21723450 in words is "twenty-one million, seven hundred twenty-three thousand, four hundred fifty".