61111111181 has 2 divisors, whose sum is σ = 61111111182. Its totient is φ = 61111111180.

The previous prime is 61111111169. The next prime is 61111111249. The reversal of 61111111181 is 18111111116.

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., 49044088681 + 12067022500 = 221459^2 + 109850^2 .It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 18111111119 and 91111111181.

It is a cyclic number.

It is not a de Polignac number, because 61111111181 - 2¹⁴ = 61111094797 is a prime.

It is a super-2 number, since 2×61111111181² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61111111121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30555555590 + 30555555591.

It is an arithmetic number, because the mean of its divisors is an integer number (30555555591).

Almost surely, 2^61111111181 is an apocalyptic number.

It is an amenable number.

61111111181 is a deficient number, since it is larger than the sum of its proper divisors (1).

61111111181 is an equidigital number, since it uses as much as digits as its factorization.

61111111181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48, while the sum is 23.

Adding to 61111111181 its reverse (18111111116), we get a palindrome (79222222297).

The spelling of 61111111181 in words is "sixty-one billion, one hundred eleven million, one hundred eleven thousand, one hundred eighty-one".