20730161 has 4 divisors (see below), whose sum is σ = 20943972. Its totient is φ = 20516352.

The previous prime is 20730131. The next prime is 20730167. The reversal of 20730161 is 16103702.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16103702 = 2 ⋅8051851.

It can be written as a sum of positive squares in 2 ways, for example, as 13542400 + 7187761 = 3680^2 + 2681^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20730161 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20730167) 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 3 ways as a sum of consecutive naturals, for example, 106760 + ... + 106953.

It is an arithmetic number, because the mean of its divisors is an integer number (5235993).

Almost surely, 2^20730161 is an apocalyptic number.

It is an amenable number.

20730161 is a deficient number, since it is larger than the sum of its proper divisors (213811).

20730161 is an equidigital number, since it uses as much as digits as its factorization.

20730161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213810.

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 20730161 is about 4553.0386556672. The cubic root of 20730161 is about 274.7056288072.

Adding to 20730161 its reverse (16103702), we get a palindrome (36833863).

The spelling of 20730161 in words is "twenty million, seven hundred thirty thousand, one hundred sixty-one".