981999999 has 24 divisors (see below), whose sum is σ = 1450874880. Its totient is φ = 639742608.

The previous prime is 981999983. The next prime is 982000007. The reversal of 981999999 is 999999189.

It is a happy number.

981999999 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 981999999 - 2⁴ = 981999983 is a prime.

981999999 is a modest number, since divided by 99999 gives 9819 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981999929) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 353514 + ... + 356280.

It is an arithmetic number, because the mean of its divisors is an integer number (60453120).

Almost surely, 2^981999999 is an apocalyptic number.

981999999 is a deficient number, since it is larger than the sum of its proper divisors (468874881).

981999999 is a wasteful number, since it uses less digits than its factorization.

981999999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3659 (or 3656 counting only the distinct ones).

The product of its digits is 38263752, while the sum is 72.

The square root of 981999999 is about 31336.8792160292. The cubic root of 981999999 is about 993.9636352848.

The spelling of 981999999 in words is "nine hundred eighty-one million, nine hundred ninety-nine thousand, nine hundred ninety-nine".