115666021 has 2 divisors, whose sum is σ = 115666022. Its totient is φ = 115666020.

The previous prime is 115666003. The next prime is 115666039. The reversal of 115666021 is 120666511.

It is a balanced prime because it is at equal distance from previous prime (115666003) and next prime (115666039).

It can be written as a sum of positive squares in only one way, i.e., 111197025 + 4468996 = 10545^2 + 2114^2 .

It is a cyclic number.

It is not a de Polignac number, because 115666021 - 2¹⁵ = 115633253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (115666051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57833010 + 57833011.

It is an arithmetic number, because the mean of its divisors is an integer number (57833011).

Almost surely, 2^115666021 is an apocalyptic number.

It is an amenable number.

115666021 is a deficient number, since it is larger than the sum of its proper divisors (1).

115666021 is an equidigital number, since it uses as much as digits as its factorization.

115666021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 115666021 is about 10754.8138524105. The cubic root of 115666021 is about 487.2313958398.

The spelling of 115666021 in words is "one hundred fifteen million, six hundred sixty-six thousand, twenty-one".