21227730 has 64 divisors (see below), whose sum is σ = 54587520. Its totient is φ = 5264384.

The previous prime is 21227711. The next prime is 21227753. The reversal of 21227730 is 3772212.

It is a self number, because there is not a number n which added to its sum of digits gives 21227730.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 54376 + ... + 54764.

It is an arithmetic number, because the mean of its divisors is an integer number (852930).

Almost surely, 2^21227730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21227730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27293760).

21227730 is an abundant number, since it is smaller than the sum of its proper divisors (33359790).

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

21227730 is a wasteful number, since it uses less digits than its factorization.

21227730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523.

The product of its (nonzero) digits is 1176, while the sum is 24.

The square root of 21227730 is about 4607.3560748004. The cubic root of 21227730 is about 276.8861196525.

Adding to 21227730 its reverse (3772212), we get a palindrome (24999942).

The spelling of 21227730 in words is "twenty-one million, two hundred twenty-seven thousand, seven hundred thirty".