111666155021 has 2 divisors, whose sum is σ = 111666155022. Its totient is φ = 111666155020.

The previous prime is 111666155009. The next prime is 111666155039. The reversal of 111666155021 is 120551666111.

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., 107970730921 + 3695424100 = 328589^2 + 60790^2 .

It is an emirp because it is prime and its reverse (120551666111) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-111666155021 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111666151021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55833077510 + 55833077511.

It is an arithmetic number, because the mean of its divisors is an integer number (55833077511).

Almost surely, 2^111666155021 is an apocalyptic number.

It is an amenable number.

111666155021 is a deficient number, since it is larger than the sum of its proper divisors (1).

111666155021 is an equidigital number, since it uses as much as digits as its factorization.

111666155021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10800, while the sum is 35.

The spelling of 111666155021 in words is "one hundred eleven billion, six hundred sixty-six million, one hundred fifty-five thousand, twenty-one".