25128778 has 4 divisors (see below), whose sum is σ = 37693170. Its totient is φ = 12564388.

The previous prime is 25128721. The next prime is 25128781. The reversal of 25128778 is 87782152.

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., 20187049 + 4941729 = 4493^2 + 2223^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 25128778.

It is an unprimeable number.

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, 6282193 + ... + 6282196.

Almost surely, 2^25128778 is an apocalyptic number.

25128778 is a deficient number, since it is larger than the sum of its proper divisors (12564392).

25128778 is a wasteful number, since it uses less digits than its factorization.

25128778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12564391.

The product of its digits is 62720, while the sum is 40.

The square root of 25128778 is about 5012.8612588022. The cubic root of 25128778 is about 292.9029797550.

The spelling of 25128778 in words is "twenty-five million, one hundred twenty-eight thousand, seven hundred seventy-eight".