128505680 has 20 divisors (see below), whose sum is σ = 298775892. Its totient is φ = 51402240.

The previous prime is 128505679. The next prime is 128505733. The reversal of 128505680 is 86505821.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 46566976 + 81938704 = 6824^2 + 9052^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-4 number, since 4×128505680⁴ (a number of 34 digits) contains 4444 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 128505680.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 803081 + ... + 803240.

Almost surely, 2^128505680 is an apocalyptic number.

128505680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

128505680 is an abundant number, since it is smaller than the sum of its proper divisors (170270212).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

128505680 is a wasteful number, since it uses less digits than its factorization.

128505680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1606334 (or 1606328 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 128505680 is about 11336.0345800461. The cubic root of 128505680 is about 504.6312113224.

The spelling of 128505680 in words is "one hundred twenty-eight million, five hundred five thousand, six hundred eighty".