20855511181 has 4 divisors (see below), whose sum is σ = 20929730364. Its totient is φ = 20781292000.

The previous prime is 20855511179. The next prime is 20855511197. The reversal of 20855511181 is 18111555802.

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 18964044100 + 1891467081 = 137710^2 + 43491^2 .

It is a cyclic number.

It is not a de Polignac number, because 20855511181 - 2¹ = 20855511179 is a prime.

It is a super-2 number, since 2×20855511181² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20855511181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20855511151) 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, 37109170 + ... + 37109731.

It is an arithmetic number, because the mean of its divisors is an integer number (5232432591).

Almost surely, 2^20855511181 is an apocalyptic number.

It is an amenable number.

20855511181 is a deficient number, since it is larger than the sum of its proper divisors (74219183).

20855511181 is an equidigital number, since it uses as much as digits as its factorization.

20855511181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74219182.

The product of its (nonzero) digits is 16000, while the sum is 37.

The spelling of 20855511181 in words is "twenty billion, eight hundred fifty-five million, five hundred eleven thousand, one hundred eighty-one".