7861978 has 4 divisors (see below), whose sum is σ = 11792970. Its totient is φ = 3930988.

The previous prime is 7861969. The next prime is 7861999. The reversal of 7861978 is 8791687.

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., 6953769 + 908209 = 2637^2 + 953^2 .

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, 1965493 + ... + 1965496.

Almost surely, 2^7861978 is an apocalyptic number.

7861978 is a deficient number, since it is larger than the sum of its proper divisors (3930992).

7861978 is a wasteful number, since it uses less digits than its factorization.

7861978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3930991.

The product of its digits is 169344, while the sum is 46.

The square root of 7861978 is about 2803.9218962018. The cubic root of 7861978 is about 198.8431379195.

The spelling of 7861978 in words is "seven million, eight hundred sixty-one thousand, nine hundred seventy-eight".