989978987 has 2 divisors, whose sum is σ = 989978988. Its totient is φ = 989978986.

The previous prime is 989978959. The next prime is 989978999. The reversal of 989978987 is 789879989.

989978987 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 989978987 - 2¹² = 989974891 is a prime.

It is not a weakly prime, because it can be changed into another prime (989978687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494989493 + 494989494.

It is an arithmetic number, because the mean of its divisors is an integer number (494989494).

Almost surely, 2^989978987 is an apocalyptic number.

989978987 is a deficient number, since it is larger than the sum of its proper divisors (1).

989978987 is an equidigital number, since it uses as much as digits as its factorization.

989978987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 164602368, while the sum is 74.

The square root of 989978987 is about 31463.9315248429. The cubic root of 989978987 is about 996.6484419412.

The spelling of 989978987 in words is "nine hundred eighty-nine million, nine hundred seventy-eight thousand, nine hundred eighty-seven".