20121225181 has 2 divisors, whose sum is σ = 20121225182. Its totient is φ = 20121225180.

The previous prime is 20121225161. The next prime is 20121225233. The reversal of 20121225181 is 18152212102.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19799022681 + 322202500 = 140709^2 + 17950^2 .

It is a cyclic number.

It is not a de Polignac number, because 20121225181 - 2⁷ = 20121225053 is a prime.

It is a super-2 number, since 2×20121225181² (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 (20121225101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060612590 + 10060612591.

It is an arithmetic number, because the mean of its divisors is an integer number (10060612591).

Almost surely, 2^20121225181 is an apocalyptic number.

It is an amenable number.

20121225181 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121225181 is an equidigital number, since it uses as much as digits as its factorization.

20121225181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 640, while the sum is 25.

Adding to 20121225181 its reverse (18152212102), we get a palindrome (38273437283).

The spelling of 20121225181 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-five thousand, one hundred eighty-one".