987123209 has 2 divisors, whose sum is σ = 987123210. Its totient is φ = 987123208.

The previous prime is 987123113. The next prime is 987123211. The reversal of 987123209 is 902321789.

It is a happy number.

987123209 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 can be written as a sum of positive squares in only one way, i.e., 978438400 + 8684809 = 31280^2 + 2947^2 .

It is a cyclic number.

It is not a de Polignac number, because 987123209 - 2²⁰ = 986074633 is a prime.

Together with 987123211, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (987123409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 493561604 + 493561605.

It is an arithmetic number, because the mean of its divisors is an integer number (493561605).

Almost surely, 2^987123209 is an apocalyptic number.

It is an amenable number.

987123209 is a deficient number, since it is larger than the sum of its proper divisors (1).

987123209 is an equidigital number, since it uses as much as digits as its factorization.

987123209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54432, while the sum is 41.

The square root of 987123209 is about 31418.5169764583. The cubic root of 987123209 is about 995.6891798660.

The spelling of 987123209 in words is "nine hundred eighty-seven million, one hundred twenty-three thousand, two hundred nine".