9978891 has 8 divisors (see below), whose sum is σ = 14328720. Its totient is φ = 6140832.

The previous prime is 9978889. The next prime is 9978911. The reversal of 9978891 is 1988799.

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

It is not a de Polignac number, because 9978891 - 2¹ = 9978889 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9978811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 127896 + ... + 127973.

It is an arithmetic number, because the mean of its divisors is an integer number (1791090).

Almost surely, 2^9978891 is an apocalyptic number.

9978891 is a deficient number, since it is larger than the sum of its proper divisors (4349829).

9978891 is a wasteful number, since it uses less digits than its factorization.

9978891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255885.

The product of its digits is 326592, while the sum is 51.

The square root of 9978891 is about 3158.9382710018. The cubic root of 9978891 is about 215.2917690056.

The spelling of 9978891 in words is "nine million, nine hundred seventy-eight thousand, eight hundred ninety-one".