128815501 has 4 divisors (see below), whose sum is σ = 130091004. Its totient is φ = 127540000.

The previous prime is 128815499. The next prime is 128815507. The reversal of 128815501 is 105518821.

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 115132900 + 13682601 = 10730^2 + 3699^2 .

It is a cyclic number.

It is not a de Polignac number, because 128815501 - 2¹ = 128815499 is a prime.

It is a super-4 number, since 4×128815501⁴ (a number of 34 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128815507) 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, 637600 + ... + 637801.

It is an arithmetic number, because the mean of its divisors is an integer number (32522751).

Almost surely, 2^128815501 is an apocalyptic number.

It is an amenable number.

128815501 is a deficient number, since it is larger than the sum of its proper divisors (1275503).

128815501 is a wasteful number, since it uses less digits than its factorization.

128815501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1275502.

The product of its (nonzero) digits is 3200, while the sum is 31.

The square root of 128815501 is about 11349.6916698208. The cubic root of 128815501 is about 505.0364330151.

The spelling of 128815501 in words is "one hundred twenty-eight million, eight hundred fifteen thousand, five hundred one".