7778978 has 4 divisors (see below), whose sum is σ = 11668470. Its totient is φ = 3889488.

The previous prime is 7778963. The next prime is 7778983. The reversal of 7778978 is 8798777.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8798777 = 13 ⋅676829.

It can be written as a sum of positive squares in only one way, i.e., 7360369 + 418609 = 2713^2 + 647^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1944743 + ... + 1944746.

Almost surely, 2^7778978 is an apocalyptic number.

7778978 is a deficient number, since it is larger than the sum of its proper divisors (3889492).

7778978 is a wasteful number, since it uses less digits than its factorization.

7778978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3889491.

The product of its digits is 1382976, while the sum is 53.

The square root of 7778978 is about 2789.0819278035. The cubic root of 7778978 is about 198.1409227020.

The spelling of 7778978 in words is "seven million, seven hundred seventy-eight thousand, nine hundred seventy-eight".