111781861 has 2 divisors, whose sum is σ = 111781862. Its totient is φ = 111781860.

The previous prime is 111781843. The next prime is 111781991. The reversal of 111781861 is 168187111.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 98128836 + 13653025 = 9906^2 + 3695^2 .

It is a cyclic number.

It is not a de Polignac number, because 111781861 - 2⁹ = 111781349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111781261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55890930 + 55890931.

It is an arithmetic number, because the mean of its divisors is an integer number (55890931).

Almost surely, 2^111781861 is an apocalyptic number.

It is an amenable number.

111781861 is a deficient number, since it is larger than the sum of its proper divisors (1).

111781861 is an equidigital number, since it uses as much as digits as its factorization.

111781861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 34.

The square root of 111781861 is about 10572.6941221242. The cubic root of 111781861 is about 481.7153053828.

The spelling of 111781861 in words is "one hundred eleven million, seven hundred eighty-one thousand, eight hundred sixty-one".