866121181 has 2 divisors, whose sum is σ = 866121182. Its totient is φ = 866121180.

The previous prime is 866121173. The next prime is 866121203. The reversal of 866121181 is 181121668.

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., 839029156 + 27092025 = 28966^2 + 5205^2 .

It is a cyclic number.

It is not a de Polignac number, because 866121181 - 2³ = 866121173 is a prime.

It is a super-2 number, since 2×866121181² = 1500331800353669522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866121131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433060590 + 433060591.

It is an arithmetic number, because the mean of its divisors is an integer number (433060591).

Almost surely, 2^866121181 is an apocalyptic number.

It is an amenable number.

866121181 is a deficient number, since it is larger than the sum of its proper divisors (1).

866121181 is an equidigital number, since it uses as much as digits as its factorization.

866121181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 34.

The square root of 866121181 is about 29429.9368161061. The cubic root of 866121181 is about 953.2194305236.

The spelling of 866121181 in words is "eight hundred sixty-six million, one hundred twenty-one thousand, one hundred eighty-one".