866409989 has 2 divisors, whose sum is σ = 866409990. Its totient is φ = 866409988.

The previous prime is 866409983. The next prime is 866410007. The reversal of 866409989 is 989904668.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 758561764 + 107848225 = 27542^2 + 10385^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-866409989 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866409983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433204994 + 433204995.

It is an arithmetic number, because the mean of its divisors is an integer number (433204995).

Almost surely, 2^866409989 is an apocalyptic number.

It is an amenable number.

866409989 is a deficient number, since it is larger than the sum of its proper divisors (1).

866409989 is an equidigital number, since it uses as much as digits as its factorization.

866409989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6718464, while the sum is 59.

The square root of 866409989 is about 29434.8431115235. The cubic root of 866409989 is about 953.3253690496.

The spelling of 866409989 in words is "eight hundred sixty-six million, four hundred nine thousand, nine hundred eighty-nine".