21745230 has 48 divisors (see below), whose sum is σ = 56525040. Its totient is φ = 5351424.

The previous prime is 21745201. The next prime is 21745247. The reversal of 21745230 is 3254712.

It is a self number, because there is not a number n which added to its sum of digits gives 21745230.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2926 + ... + 7214.

It is an arithmetic number, because the mean of its divisors is an integer number (1177605).

Almost surely, 2^21745230 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21745230, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28262520).

21745230 is an abundant number, since it is smaller than the sum of its proper divisors (34779810).

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

21745230 is a wasteful number, since it uses less digits than its factorization.

21745230 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4325 (or 4312 counting only the distinct ones).

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

The square root of 21745230 is about 4663.1781008235. The cubic root of 21745230 is about 279.1181011035.

Adding to 21745230 its reverse (3254712), we get a palindrome (24999942).

The spelling of 21745230 in words is "twenty-one million, seven hundred forty-five thousand, two hundred thirty".