169978991909 has 2 divisors, whose sum is σ = 169978991910. Its totient is φ = 169978991908.

The previous prime is 169978991899. The next prime is 169978991957. The reversal of 169978991909 is 909199879961.

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., 85452151684 + 84526840225 = 292322^2 + 290735^2 .

It is a cyclic number.

It is not a de Polignac number, because 169978991909 - 2²⁴ = 169962214693 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 169978991909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (169978991999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84989495954 + 84989495955.

It is an arithmetic number, because the mean of its divisors is an integer number (84989495955).

Almost surely, 2^169978991909 is an apocalyptic number.

It is an amenable number.

169978991909 is a deficient number, since it is larger than the sum of its proper divisors (1).

169978991909 is an equidigital number, since it uses as much as digits as its factorization.

169978991909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 178564176, while the sum is 77.

The spelling of 169978991909 in words is "one hundred sixty-nine billion, nine hundred seventy-eight million, nine hundred ninety-one thousand, nine hundred nine".