28135987 has 4 divisors (see below), whose sum is σ = 30693816. Its totient is φ = 25578160.

The previous prime is 28135973. The next prime is 28135997. The reversal of 28135987 is 78953182.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28135987 - 2¹¹ = 28133939 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28135927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1278898 + ... + 1278919.

It is an arithmetic number, because the mean of its divisors is an integer number (7673454).

Almost surely, 2^28135987 is an apocalyptic number.

28135987 is a deficient number, since it is larger than the sum of its proper divisors (2557829).

28135987 is a wasteful number, since it uses less digits than its factorization.

28135987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2557828.

The product of its digits is 120960, while the sum is 43.

The square root of 28135987 is about 5304.3366220480. The cubic root of 28135987 is about 304.1496947141.

The spelling of 28135987 in words is "twenty-eight million, one hundred thirty-five thousand, nine hundred eighty-seven".