9987978 has 64 divisors (see below), whose sum is σ = 26836992. Its totient is φ = 2393280.

The previous prime is 9987973. The next prime is 9987979. The reversal of 9987978 is 8797899.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (9987973) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 5175 + ... + 6837.

It is an arithmetic number, because the mean of its divisors is an integer number (419328).

Almost surely, 2^9987978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9987978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13418496).

9987978 is an abundant number, since it is smaller than the sum of its proper divisors (16849014).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9987978 is a wasteful number, since it uses less digits than its factorization.

9987978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1699.

The product of its digits is 2286144, while the sum is 57.

The square root of 9987978 is about 3160.3762434242. The cubic root of 9987978 is about 215.3570990031.

The spelling of 9987978 in words is "nine million, nine hundred eighty-seven thousand, nine hundred seventy-eight".