128316204168021 has 40 divisors (see below), whose sum is σ = 199298521924920. Its totient is φ = 82175077418112.

The previous prime is 128316204167999. The next prime is 128316204168023. The reversal of 128316204168021 is 120861402613821.

128316204168021 is a `hidden beast` number, since 1 + 2 + 8 + 3 + 1 + 620 + 4 + 16 + 8 + 0 + 2 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 94299151100625 + 34017053067396 = 9710775^2 + 5832414^2 .

It is not a de Polignac number, because 128316204168021 - 2⁵ = 128316204167989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128316204168023) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 138181626 + ... + 139107131.

It is an arithmetic number, because the mean of its divisors is an integer number (4982463048123).

Almost surely, 2^{128316204168021} is an apocalyptic number.

It is an amenable number.

128316204168021 is a deficient number, since it is larger than the sum of its proper divisors (70982317756899).

128316204168021 is a wasteful number, since it uses less digits than its factorization.

128316204168021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277288995 (or 277288986 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The spelling of 128316204168021 in words is "one hundred twenty-eight trillion, three hundred sixteen billion, two hundred four million, one hundred sixty-eight thousand, twenty-one".