7921978 has 8 divisors (see below), whose sum is σ = 11988468. Its totient is φ = 3925824.

The previous prime is 7921943. The next prime is 7921981. The reversal of 7921978 is 8791297.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6036849 + 1885129 = 2457^2 + 1373^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17301 + ... + 17752.

Almost surely, 2^7921978 is an apocalyptic number.

7921978 is a deficient number, since it is larger than the sum of its proper divisors (4066490).

7921978 is a wasteful number, since it uses less digits than its factorization.

7921978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35168.

The product of its digits is 63504, while the sum is 43.

The square root of 7921978 is about 2814.6008598023. The cubic root of 7921978 is about 199.3476914474.

It can be divided in two parts, 79219 and 78, that added together give a palindrome (79297).

The spelling of 7921978 in words is "seven million, nine hundred twenty-one thousand, nine hundred seventy-eight".