28978 has 4 divisors (see below), whose sum is σ = 43470. Its totient is φ = 14488.

The previous prime is 28961. The next prime is 28979. The reversal of 28978 is 87982.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87982 = 2 ⋅43991.

It can be written as a sum of positive squares in only one way, i.e., 27889 + 1089 = 167^2 + 33^2 .

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (28979) by changing a digit.

28978 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7243 + ... + 7246.

2²⁸⁹⁷⁸ is an apocalyptic number.

28978 is a deficient number, since it is larger than the sum of its proper divisors (14492).

28978 is a wasteful number, since it uses less digits than its factorization.

28978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14491.

The product of its digits is 8064, while the sum is 34.

The square root of 28978 is about 170.2292571798. The cubic root of 28978 is about 30.7153972144.

It can be divided in two parts, 2 and 8978, that multiplied together give a square (17956 = 134²).

The spelling of 28978 in words is "twenty-eight thousand, nine hundred seventy-eight".