128118661 has 4 divisors (see below), whose sum is σ = 139765824. Its totient is φ = 116471500.

The previous prime is 128118643. The next prime is 128118689. The reversal of 128118661 is 166811821.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 128118661 - 2⁹ = 128118149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128118631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5823565 + ... + 5823586.

It is an arithmetic number, because the mean of its divisors is an integer number (34941456).

Almost surely, 2^128118661 is an apocalyptic number.

128118661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128118661 is a deficient number, since it is larger than the sum of its proper divisors (11647163).

128118661 is a wasteful number, since it uses less digits than its factorization.

128118661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11647162.

The product of its digits is 4608, while the sum is 34.

The square root of 128118661 is about 11318.9514090308. The cubic root of 128118661 is about 504.1241046631.

The spelling of 128118661 in words is "one hundred twenty-eight million, one hundred eighteen thousand, six hundred sixty-one".