221189646728 has 36 divisors (see below), whose sum is σ = 416995108485. Its totient is φ = 109994223616.

The previous prime is 221189646673. The next prime is 221189646761. The reversal of 221189646728 is 827646981122.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 137921618884 + 83268027844 = 371378^2 + 288562^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=332558.

It is a super-2 number, since 2×221189646728² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 341869301 + ... + 341869947.

Almost surely, 2^221189646728 is an apocalyptic number.

It is an amenable number.

221189646728 is a deficient number, since it is larger than the sum of its proper divisors (195805461757).

221189646728 is an frugal number, since it uses more digits than its factorization.

221189646728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1814 (or 906 counting only the distinct ones).

The product of its digits is 4644864, while the sum is 56.

The spelling of 221189646728 in words is "two hundred twenty-one billion, one hundred eighty-nine million, six hundred forty-six thousand, seven hundred twenty-eight".