7128778 has 4 divisors (see below), whose sum is σ = 10693170. Its totient is φ = 3564388.

The previous prime is 7128767. The next prime is 7128799. The reversal of 7128778 is 8778217.

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: 8778217 = 7 ⋅1254031.

It can be written as a sum of positive squares in only one way, i.e., 4809249 + 2319529 = 2193^2 + 1523^2 .

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 7128778.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1782193 + ... + 1782196.

Almost surely, 2^7128778 is an apocalyptic number.

7128778 is a deficient number, since it is larger than the sum of its proper divisors (3564392).

7128778 is a wasteful number, since it uses less digits than its factorization.

7128778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3564391.

The product of its digits is 43904, while the sum is 40.

The square root of 7128778 is about 2669.9771534603. The cubic root of 7128778 is about 192.4590614017.

The spelling of 7128778 in words is "seven million, one hundred twenty-eight thousand, seven hundred seventy-eight".