163811961 has 6 divisors (see below), whose sum is σ = 236617290. Its totient is φ = 109207968.

The previous prime is 163811959. The next prime is 163812007. The reversal of 163811961 is 169118361.

It is a happy number.

163811961 is a `hidden beast` number, since 1 + 638 + 1 + 19 + 6 + 1 = 666.

163811961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 161798400 + 2013561 = 12720^2 + 1419^2 .

It is not a de Polignac number, because 163811961 - 2¹ = 163811959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (163811561) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9100656 + ... + 9100673.

It is an arithmetic number, because the mean of its divisors is an integer number (39436215).

Almost surely, 2^163811961 is an apocalyptic number.

It is an amenable number.

163811961 is a deficient number, since it is larger than the sum of its proper divisors (72805329).

163811961 is a wasteful number, since it uses less digits than its factorization.

163811961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18201335 (or 18201332 counting only the distinct ones).

The product of its digits is 7776, while the sum is 36.

The square root of 163811961 is about 12798.9046796982. The cubic root of 163811961 is about 547.1610863018.

The spelling of 163811961 in words is "one hundred sixty-three million, eight hundred eleven thousand, nine hundred sixty-one".