161505 has 24 divisors (see below), whose sum is σ = 290472. Its totient is φ = 82944.

The previous prime is 161503. The next prime is 161507. The reversal of 161505 is 505161.

161505 is a `hidden beast` number, since 161 + 505 = 666.

It is an interprime number because it is at equal distance from previous prime (161503) and next prime (161507).

It can be written as a sum of positive squares in 4 ways, for example, as 40401 + 121104 = 201^2 + 348^2 .

It is not a de Polignac number, because 161505 - 2¹ = 161503 is a prime.

161505 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (161503) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1617 + ... + 1713.

It is an arithmetic number, because the mean of its divisors is an integer number (12103).

2¹⁶¹⁵⁰⁵ is an apocalyptic number.

161505 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

161505 is a deficient number, since it is larger than the sum of its proper divisors (128967).

161505 is a wasteful number, since it uses less digits than its factorization.

161505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145 (or 142 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 161505 is about 401.8768468076. The cubic root of 161505 is about 54.4580380082.

Adding to 161505 its reverse (505161), we get a palindrome (666666).

It can be divided in two parts, 161 and 505, that added together give a palindrome (666).

The spelling of 161505 in words is "one hundred sixty-one thousand, five hundred five".