163661809 has 2 divisors, whose sum is σ = 163661810. Its totient is φ = 163661808.

The previous prime is 163661777. The next prime is 163661821. The reversal of 163661809 is 908166361.

163661809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 159264400 + 4397409 = 12620^2 + 2097^2 .

It is a cyclic number.

It is not a de Polignac number, because 163661809 - 2⁵ = 163661777 is a prime.

It is not a weakly prime, because it can be changed into another prime (163661009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81830904 + 81830905.

It is an arithmetic number, because the mean of its divisors is an integer number (81830905).

Almost surely, 2^163661809 is an apocalyptic number.

It is an amenable number.

163661809 is a deficient number, since it is larger than the sum of its proper divisors (1).

163661809 is an equidigital number, since it uses as much as digits as its factorization.

163661809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 163661809 is about 12793.0375204640. The cubic root of 163661809 is about 546.9938570677.

The spelling of 163661809 in words is "one hundred sixty-three million, six hundred sixty-one thousand, eight hundred nine".