20558111161 has 9 divisors (see below), whose sum is σ = 23915705061. Its totient is φ = 17620377852.

The previous prime is 20558111159. The next prime is 20558111173. The reversal of 20558111161 is 16111185502.

The square root of 20558111161 is 143381.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 20558111161 - 2¹ = 20558111159 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20558111141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 993426 + ... + 1013908.

Almost surely, 2^20558111161 is an apocalyptic number.

20558111161 is the 143381-st square number.

20558111161 is the 71691-st centered octagonal number.

It is an amenable number.

20558111161 is a deficient number, since it is larger than the sum of its proper divisors (3357593900).

20558111161 is an frugal number, since it uses more digits than its factorization.

20558111161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40980 (or 20490 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 31.

Adding to 20558111161 its reverse (16111185502), we get a palindrome (36669296663).

The spelling of 20558111161 in words is "twenty billion, five hundred fifty-eight million, one hundred eleven thousand, one hundred sixty-one".