28257778 has 4 divisors (see below), whose sum is σ = 42386670. Its totient is φ = 14128888.

The previous prime is 28257773. The next prime is 28257781. The reversal of 28257778 is 87775282.

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., 17413929 + 10843849 = 4173^2 + 3293^2 .

It is not an unprimeable number, because it can be changed into a prime (28257773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7064443 + ... + 7064446.

Almost surely, 2^28257778 is an apocalyptic number.

28257778 is a deficient number, since it is larger than the sum of its proper divisors (14128892).

28257778 is a wasteful number, since it uses less digits than its factorization.

28257778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14128891.

The product of its digits is 439040, while the sum is 46.

The square root of 28257778 is about 5315.8045487019. The cubic root of 28257778 is about 304.5879161192.

The spelling of 28257778 in words is "twenty-eight million, two hundred fifty-seven thousand, seven hundred seventy-eight".