161778105 has 12 divisors (see below), whose sum is σ = 280415460. Its totient is φ = 86281632.

The previous prime is 161778079. The next prime is 161778107. The reversal of 161778105 is 501877161.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 48483369 + 113294736 = 6963^2 + 10644^2 .

It is not a de Polignac number, because 161778105 - 2⁵ = 161778073 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161778105.

It is not an unprimeable number, because it can be changed into a prime (161778107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1797490 + ... + 1797579.

It is an arithmetic number, because the mean of its divisors is an integer number (23367955).

Almost surely, 2^161778105 is an apocalyptic number.

161778105 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

161778105 is a deficient number, since it is larger than the sum of its proper divisors (118637355).

161778105 is a wasteful number, since it uses less digits than its factorization.

161778105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3595080 (or 3595077 counting only the distinct ones).

The product of its (nonzero) digits is 11760, while the sum is 36.

The square root of 161778105 is about 12719.2022155480. The cubic root of 161778105 is about 544.8871690784.

The spelling of 161778105 in words is "one hundred sixty-one million, seven hundred seventy-eight thousand, one hundred five".