20161181 has 4 divisors (see below), whose sum is σ = 20188572. Its totient is φ = 20133792.

The previous prime is 20161157. The next prime is 20161199. The reversal of 20161181 is 18116102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17355556 + 2805625 = 4166^2 + 1675^2 .

It is a cyclic number.

It is not a de Polignac number, because 20161181 - 2¹⁴ = 20144797 is a prime.

It is a super-2 number, since 2×20161181² = 812946438629522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20161151) 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 3 ways as a sum of consecutive naturals, for example, 12560 + ... + 14073.

It is an arithmetic number, because the mean of its divisors is an integer number (5047143).

Almost surely, 2^20161181 is an apocalyptic number.

It is an amenable number.

20161181 is a deficient number, since it is larger than the sum of its proper divisors (27391).

20161181 is an equidigital number, since it uses as much as digits as its factorization.

20161181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27390.

The product of its (nonzero) digits is 96, while the sum is 20.

The square root of 20161181 is about 4490.1203770055. The cubic root of 20161181 is about 272.1689991063.

Adding to 20161181 its reverse (18116102), we get a palindrome (38277283).

The spelling of 20161181 in words is "twenty million, one hundred sixty-one thousand, one hundred eighty-one".