128221025785 has 4 divisors (see below), whose sum is σ = 153865230948. Its totient is φ = 102576820624.

The previous prime is 128221025783. The next prime is 128221025789. The reversal of 128221025785 is 587520122821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 72742405264 + 55478620521 = 269708^2 + 235539^2 .

It is a cyclic number.

It is not a de Polignac number, because 128221025785 - 2¹ = 128221025783 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128221025783) 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, 12822102574 + ... + 12822102583.

It is an arithmetic number, because the mean of its divisors is an integer number (38466307737).

Almost surely, 2^128221025785 is an apocalyptic number.

It is an amenable number.

128221025785 is a deficient number, since it is larger than the sum of its proper divisors (25644205163).

128221025785 is an equidigital number, since it uses as much as digits as its factorization.

128221025785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25644205162.

The product of its (nonzero) digits is 179200, while the sum is 43.

The spelling of 128221025785 in words is "one hundred twenty-eight billion, two hundred twenty-one million, twenty-five thousand, seven hundred eighty-five".