28988133557 has 4 divisors (see below), whose sum is σ = 28995077676. Its totient is φ = 28981189440.

The previous prime is 28988133533. The next prime is 28988133569. The reversal of 28988133557 is 75533188982.

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 13181106481 + 15807027076 = 114809^2 + 125726^2 .

It is a cyclic number.

It is not a de Polignac number, because 28988133557 - 2²⁸ = 28719698101 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28988133496 and 28988133505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28988193557) 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, 3465794 + ... + 3474147.

It is an arithmetic number, because the mean of its divisors is an integer number (7248769419).

Almost surely, 2^28988133557 is an apocalyptic number.

It is an amenable number.

28988133557 is a deficient number, since it is larger than the sum of its proper divisors (6944119).

28988133557 is an equidigital number, since it uses as much as digits as its factorization.

28988133557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6944118.

The product of its digits is 14515200, while the sum is 59.

The spelling of 28988133557 in words is "twenty-eight billion, nine hundred eighty-eight million, one hundred thirty-three thousand, five hundred fifty-seven".