128645681 has 16 divisors (see below), whose sum is σ = 140807808. Its totient is φ = 117062400.

The previous prime is 128645669. The next prime is 128645683. The reversal of 128645681 is 186546821.

It is a cyclic number.

It is not a de Polignac number, because 128645681 - 2¹⁰ = 128644657 is a prime.

It is a super-2 number, since 2×128645681² = 33099422479907522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128645683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62966 + ... + 64976.

It is an arithmetic number, because the mean of its divisors is an integer number (8800488).

Almost surely, 2^128645681 is an apocalyptic number.

It is an amenable number.

128645681 is a deficient number, since it is larger than the sum of its proper divisors (12162127).

128645681 is a wasteful number, since it uses less digits than its factorization.

128645681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2152.

The product of its digits is 92160, while the sum is 41.

The square root of 128645681 is about 11342.2079420190. The cubic root of 128645681 is about 504.8144022742.

The spelling of 128645681 in words is "one hundred twenty-eight million, six hundred forty-five thousand, six hundred eighty-one".