128628661 has 8 divisors (see below), whose sum is σ = 147254400. Its totient is φ = 110065488.

The previous prime is 128628649. The next prime is 128628671. The reversal of 128628661 is 166826821.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 128628661 - 2⁵ = 128628629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128628671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11146 + ... + 19531.

It is an arithmetic number, because the mean of its divisors is an integer number (18406800).

Almost surely, 2^128628661 is an apocalyptic number.

It is an amenable number.

128628661 is a deficient number, since it is larger than the sum of its proper divisors (18625739).

128628661 is an equidigital number, since it uses as much as digits as its factorization.

128628661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31283.

The product of its digits is 55296, while the sum is 40.

The square root of 128628661 is about 11341.4576223694. The cubic root of 128628661 is about 504.7921387464.

The spelling of 128628661 in words is "one hundred twenty-eight million, six hundred twenty-eight thousand, six hundred sixty-one".