128125657221 has 16 divisors (see below), whose sum is σ = 175066959936. Its totient is φ = 83306635776.

The previous prime is 128125657207. The next prime is 128125657267. The reversal of 128125657221 is 122756521821.

It is a de Polignac number, because none of the positive numbers 2^k-128125657221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128125657021) 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 15 ways as a sum of consecutive naturals, for example, 651090 + ... + 824723.

It is an arithmetic number, because the mean of its divisors is an integer number (10941684996).

Almost surely, 2^128125657221 is an apocalyptic number.

It is an amenable number.

128125657221 is a deficient number, since it is larger than the sum of its proper divisors (46941302715).

128125657221 is a wasteful number, since it uses less digits than its factorization.

128125657221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1476532.

The product of its digits is 134400, while the sum is 42.

The spelling of 128125657221 in words is "one hundred twenty-eight billion, one hundred twenty-five million, six hundred fifty-seven thousand, two hundred twenty-one".