20531161 has 4 divisors (see below), whose sum is σ = 23464192. Its totient is φ = 17598132.

The previous prime is 20531107. The next prime is 20531171. The reversal of 20531161 is 16113502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20531161 - 2¹⁷ = 20400089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20531171) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1466505 + ... + 1466518.

It is an arithmetic number, because the mean of its divisors is an integer number (5866048).

Almost surely, 2^20531161 is an apocalyptic number.

It is an amenable number.

20531161 is a deficient number, since it is larger than the sum of its proper divisors (2933031).

20531161 is an equidigital number, since it uses as much as digits as its factorization.

20531161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2933030.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 20531161 is about 4531.1324191641. The cubic root of 20531161 is about 273.8237851466.

Adding to 20531161 its reverse (16113502), we get a palindrome (36644663).

The spelling of 20531161 in words is "twenty million, five hundred thirty-one thousand, one hundred sixty-one".