989978 has 16 divisors (see below), whose sum is σ = 1715904. Its totient is φ = 423360.

The previous prime is 989977. The next prime is 989981. The reversal of 989978 is 879989.

It is not an unprimeable number, because it can be changed into a prime (989971) 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 7 ways as a sum of consecutive naturals, for example, 950 + ... + 1697.

It is an arithmetic number, because the mean of its divisors is an integer number (107244).

2⁹⁸⁹⁹⁷⁸ is an apocalyptic number.

989978 is a deficient number, since it is larger than the sum of its proper divisors (725926).

989978 is a wasteful number, since it uses less digits than its factorization.

989978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2677.

The product of its digits is 326592, while the sum is 50.

The square root of 989978 is about 994.9763816292. The cubic root of 989978 is about 99.6648110725.

The spelling of 989978 in words is "nine hundred eighty-nine thousand, nine hundred seventy-eight".