20121220181 has 2 divisors, whose sum is σ = 20121220182. Its totient is φ = 20121220180.

The previous prime is 20121220159. The next prime is 20121220187. The reversal of 20121220181 is 18102212102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13093080625 + 7028139556 = 114425^2 + 83834^2 .

It is a cyclic number.

It is not a de Polignac number, because 20121220181 - 2⁶ = 20121220117 is a prime.

It is a super-2 number, since 2×20121220181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20121220187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060610090 + 10060610091.

It is an arithmetic number, because the mean of its divisors is an integer number (10060610091).

Almost surely, 2^20121220181 is an apocalyptic number.

It is an amenable number.

20121220181 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121220181 is an equidigital number, since it uses as much as digits as its factorization.

20121220181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 20121220181 its reverse (18102212102), we get a palindrome (38223432283).

The spelling of 20121220181 in words is "twenty billion, one hundred twenty-one million, two hundred twenty thousand, one hundred eighty-one".