28987778 has 4 divisors (see below), whose sum is σ = 43481670. Its totient is φ = 14493888.

The previous prime is 28987769. The next prime is 28987781. The reversal of 28987778 is 87778982.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87778982 = 2 ⋅43889491.

It can be written as a sum of positive squares in only one way, i.e., 23261329 + 5726449 = 4823^2 + 2393^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7246943 + ... + 7246946.

Almost surely, 2^28987778 is an apocalyptic number.

28987778 is a deficient number, since it is larger than the sum of its proper divisors (14493892).

28987778 is a wasteful number, since it uses less digits than its factorization.

28987778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14493891.

The product of its digits is 3161088, while the sum is 56.

The square root of 28987778 is about 5384.0299033345. The cubic root of 28987778 is about 307.1885157495.

The spelling of 28987778 in words is "twenty-eight million, nine hundred eighty-seven thousand, seven hundred seventy-eight".