9781978 has 8 divisors (see below), whose sum is σ = 14726772. Its totient is φ = 4873056.

The previous prime is 9781963. The next prime is 9781991. The reversal of 9781978 is 8791879.

It can be written as a sum of positive squares in 2 ways, for example, as 8334769 + 1447209 = 2887^2 + 1203^2 .

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

It is an Ulam number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8275 + ... + 9382.

Almost surely, 2^9781978 is an apocalyptic number.

9781978 is a deficient number, since it is larger than the sum of its proper divisors (4944794).

9781978 is a wasteful number, since it uses less digits than its factorization.

9781978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17936.

The product of its digits is 254016, while the sum is 49.

The square root of 9781978 is about 3127.6153855613. The cubic root of 9781978 is about 213.8662366096.

Subtracting from 9781978 its reverse (8791879), we obtain a palindrome (990099).

The spelling of 9781978 in words is "nine million, seven hundred eighty-one thousand, nine hundred seventy-eight".