989868991 has 2 divisors, whose sum is σ = 989868992. Its totient is φ = 989868990.

The previous prime is 989868989. The next prime is 989869033. The reversal of 989868991 is 199868989.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 989868991 - 2¹ = 989868989 is a prime.

Together with 989868989, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (989868491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494934495 + 494934496.

It is an arithmetic number, because the mean of its divisors is an integer number (494934496).

Almost surely, 2^989868991 is an apocalyptic number.

989868991 is a deficient number, since it is larger than the sum of its proper divisors (1).

989868991 is an equidigital number, since it uses as much as digits as its factorization.

989868991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20155392, while the sum is 67.

The square root of 989868991 is about 31462.1835065528. The cubic root of 989868991 is about 996.6115282276.

The spelling of 989868991 in words is "nine hundred eighty-nine million, eight hundred sixty-eight thousand, nine hundred ninety-one".