869811809 has 2 divisors, whose sum is σ = 869811810. Its totient is φ = 869811808.

The previous prime is 869811791. The next prime is 869811911. The reversal of 869811809 is 908118968.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 442976209 + 426835600 = 21047^2 + 20660^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-869811809 is a prime.

It is not a weakly prime, because it can be changed into another prime (869816809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 434905904 + 434905905.

It is an arithmetic number, because the mean of its divisors is an integer number (434905905).

Almost surely, 2^869811809 is an apocalyptic number.

It is an amenable number.

869811809 is a deficient number, since it is larger than the sum of its proper divisors (1).

869811809 is an equidigital number, since it uses as much as digits as its factorization.

869811809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 248832, while the sum is 50.

The square root of 869811809 is about 29492.5720987506. The cubic root of 869811809 is about 954.5714327511.

The spelling of 869811809 in words is "eight hundred sixty-nine million, eight hundred eleven thousand, eight hundred nine".