163661409 has 12 divisors (see below), whose sum is σ = 236513316. Its totient is φ = 109055232.

The previous prime is 163661389. The next prime is 163661411. The reversal of 163661409 is 904166361.

163661409 is a `hidden beast` number, since 1 + 6 + 36 + 614 + 0 + 9 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 95648400 + 68013009 = 9780^2 + 8247^2 .

It is not a de Polignac number, because 163661409 - 2¹¹ = 163659361 is a prime.

It is not an unprimeable number, because it can be changed into a prime (163661419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28249 + ... + 33545.

It is an arithmetic number, because the mean of its divisors is an integer number (19709443).

Almost surely, 2^163661409 is an apocalyptic number.

It is an amenable number.

163661409 is a deficient number, since it is larger than the sum of its proper divisors (72851907).

163661409 is a wasteful number, since it uses less digits than its factorization.

163661409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8736 (or 8733 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 163661409 is about 12793.0218869507. The cubic root of 163661409 is about 546.9934114379.

The spelling of 163661409 in words is "one hundred sixty-three million, six hundred sixty-one thousand, four hundred nine".