7921568378 has 4 divisors (see below), whose sum is σ = 11882352570. Its totient is φ = 3960784188.

The previous prime is 7921568371. The next prime is 7921568401. The reversal of 7921568378 is 8738651297.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8738651297 = 47 ⋅185928751.

It can be written as a sum of positive squares in only one way, i.e., 4305590689 + 3615977689 = 65617^2 + 60133^2 .

It is not an unprimeable number, because it can be changed into a prime (7921568371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1980392093 + ... + 1980392096.

Almost surely, 2^7921568378 is an apocalyptic number.

7921568378 is a deficient number, since it is larger than the sum of its proper divisors (3960784192).

7921568378 is a wasteful number, since it uses less digits than its factorization.

7921568378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3960784191.

The product of its digits is 5080320, while the sum is 56.

The square root of 7921568378 is about 89003.1930775520. The cubic root of 7921568378 is about 1993.4425549548.

The spelling of 7921568378 in words is "seven billion, nine hundred twenty-one million, five hundred sixty-eight thousand, three hundred seventy-eight".