989969861 has 2 divisors, whose sum is σ = 989969862.
Its totient is φ = 989969860.
The previous prime is 989969831. The next prime is 989969917. The reversal of 989969861 is 168969989.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 919241761 + 70728100 = 30319^2 + 8410^2
It is a cyclic number.
It is not a de Polignac number, because 989969861 - 214 = 989953477 is a prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (989969831) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494984930 + 494984931.
It is an arithmetic number, because the mean of its divisors is an integer number (494984931).
Almost surely, 2989969861 is an apocalyptic number.
It is an amenable number.
989969861 is a deficient number, since it is larger than the sum of its proper divisors (1).
989969861 is an equidigital number, since it uses as much as digits as its factorization.
989969861 is an evil number, because the sum of its binary digits is even.
The product of its digits is 15116544, while the sum is 65.
The square root of 989969861 is about 31463.7865013097.
The cubic root of 989969861 is about 996.6453794379.
The spelling of 989969861 in words is "nine hundred eighty-nine million, nine hundred sixty-nine thousand, eight hundred sixty-one".