666191101 has 2 divisors, whose sum is σ = 666191102. Its totient is φ = 666191100.

The previous prime is 666191059. The next prime is 666191191. The reversal of 666191101 is 101191666.

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., 414936900 + 251254201 = 20370^2 + 15851^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666191101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666191191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333095550 + 333095551.

It is an arithmetic number, because the mean of its divisors is an integer number (333095551).

Almost surely, 2^666191101 is an apocalyptic number.

It is an amenable number.

666191101 is a deficient number, since it is larger than the sum of its proper divisors (1).

666191101 is an equidigital number, since it uses as much as digits as its factorization.

666191101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 666191101 is about 25810.6780422367. The cubic root of 666191101 is about 873.3726928858.

The spelling of 666191101 in words is "six hundred sixty-six million, one hundred ninety-one thousand, one hundred one".