221728680 has 96 divisors (see below), whose sum is σ = 734277960. Its totient is φ = 58007040.

The previous prime is 221728583. The next prime is 221728691. The reversal of 221728680 is 86827122.

It is a happy number.

221728680 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 150258564 + 71470116 = 12258^2 + 8454^2 .

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 13270 + ... + 24890.

Almost surely, 2^221728680 is an apocalyptic number.

221728680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221728680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (367138980).

221728680 is an abundant number, since it is smaller than the sum of its proper divisors (512549280).

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

221728680 is a wasteful number, since it uses less digits than its factorization.

221728680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11691 (or 11684 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 221728680 is about 14890.5567390880. The cubic root of 221728680 is about 605.2581190334.

The spelling of 221728680 in words is "two hundred twenty-one million, seven hundred twenty-eight thousand, six hundred eighty".