128756661 has 8 divisors (see below), whose sum is σ = 187282464. Its totient is φ = 78034320.

The previous prime is 128756629. The next prime is 128756681. The reversal of 128756661 is 166657821.

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

It is not a de Polignac number, because 128756661 - 2⁵ = 128756629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128756611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1950826 + ... + 1950891.

It is an arithmetic number, because the mean of its divisors is an integer number (23410308).

Almost surely, 2^128756661 is an apocalyptic number.

128756661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128756661 is a deficient number, since it is larger than the sum of its proper divisors (58525803).

128756661 is a wasteful number, since it uses less digits than its factorization.

128756661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3901731.

The product of its digits is 120960, while the sum is 42.

The square root of 128756661 is about 11347.0992328436. The cubic root of 128756661 is about 504.9595249069.

The spelling of 128756661 in words is "one hundred twenty-eight million, seven hundred fifty-six thousand, six hundred sixty-one".