28777978 has 4 divisors (see below), whose sum is σ = 43166970. Its totient is φ = 14388988.

The previous prime is 28777961. The next prime is 28777979. The reversal of 28777978 is 87977782.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 28015849 + 762129 = 5293^2 + 873^2 .

It is not an unprimeable number, because it can be changed into a prime (28777979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7194493 + ... + 7194496.

Almost surely, 2^28777978 is an apocalyptic number.

28777978 is a deficient number, since it is larger than the sum of its proper divisors (14388992).

28777978 is a wasteful number, since it uses less digits than its factorization.

28777978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14388991.

The product of its digits is 2765952, while the sum is 55.

The square root of 28777978 is about 5364.5109749165. The cubic root of 28777978 is about 306.4456249505.

The spelling of 28777978 in words is "twenty-eight million, seven hundred seventy-seven thousand, nine hundred seventy-eight".