2221728660 has 36 divisors (see below), whose sum is σ = 6739244148. Its totient is φ = 592460928.

The previous prime is 2221728611. The next prime is 2221728661. The reversal of 2221728660 is 668271222.

It can be written as a sum of positive squares in 2 ways, for example, as 520661124 + 1701067536 = 22818^2 + 41244^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2221728661) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6171289 + ... + 6171648.

Almost surely, 2^2221728660 is an apocalyptic number.

2221728660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2221728660 is an abundant number, since it is smaller than the sum of its proper divisors (4517515488).

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

2221728660 is a wasteful number, since it uses less digits than its factorization.

2221728660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12342952 (or 12342947 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 2221728660 is about 47135.2167704785. The cubic root of 2221728660 is about 1304.8592616975.

Adding to 2221728660 its reverse (668271222), we get a palindrome (2889999882).

The spelling of 2221728660 in words is "two billion, two hundred twenty-one million, seven hundred twenty-eight thousand, six hundred sixty".