221458728665 has 24 divisors (see below), whose sum is σ = 282545466840. Its totient is φ = 166434444288.

The previous prime is 221458728661. The next prime is 221458728719. The reversal of 221458728665 is 566827854122.

It can be written as a sum of positive squares in 12 ways, for example, as 1932745369 + 219525983296 = 43963^2 + 468536^2 .

It is not a de Polignac number, because 221458728665 - 2² = 221458728661 is a prime.

It is a Smith number, since the sum of its digits (56) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 221458728665.

It is not an unprimeable number, because it can be changed into a prime (221458728661) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 359312 + ... + 756321.

It is an arithmetic number, because the mean of its divisors is an integer number (11772727785).

Almost surely, 2^221458728665 is an apocalyptic number.

It is an amenable number.

221458728665 is a deficient number, since it is larger than the sum of its proper divisors (61086738175).

221458728665 is a wasteful number, since it uses less digits than its factorization.

221458728665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1115741 (or 1115704 counting only the distinct ones).

The product of its digits is 12902400, while the sum is 56.

The spelling of 221458728665 in words is "two hundred twenty-one billion, four hundred fifty-eight million, seven hundred twenty-eight thousand, six hundred sixty-five".