128987636 has 18 divisors (see below), whose sum is σ = 239789718. Its totient is φ = 60699520.

The previous prime is 128987591. The next prime is 128987641. The reversal of 128987636 is 636789821.

It can be written as a sum of positive squares in 3 ways, for example, as 98803600 + 30184036 = 9940^2 + 5494^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 54635 + ... + 56946.

It is an arithmetic number, because the mean of its divisors is an integer number (13321651).

Almost surely, 2^128987636 is an apocalyptic number.

It is an amenable number.

128987636 is a deficient number, since it is larger than the sum of its proper divisors (110802082).

128987636 is a wasteful number, since it uses less digits than its factorization.

128987636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111619 (or 111600 counting only the distinct ones).

The product of its digits is 870912, while the sum is 50.

The square root of 128987636 is about 11357.2723838077. The cubic root of 128987636 is about 505.2612914397.

The spelling of 128987636 in words is "one hundred twenty-eight million, nine hundred eighty-seven thousand, six hundred thirty-six".