666101987 has 2 divisors, whose sum is σ = 666101988. Its totient is φ = 666101986.

The previous prime is 666101983. The next prime is 666101999. The reversal of 666101987 is 789101666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666101987 - 2² = 666101983 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (666101983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333050993 + 333050994.

It is an arithmetic number, because the mean of its divisors is an integer number (333050994).

Almost surely, 2^666101987 is an apocalyptic number.

666101987 is a deficient number, since it is larger than the sum of its proper divisors (1).

666101987 is an equidigital number, since it uses as much as digits as its factorization.

666101987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 666101987 is about 25808.9516834760. The cubic root of 666101987 is about 873.3337485025. Note that the first 3 decimals are identical.

The spelling of 666101987 in words is "six hundred sixty-six million, one hundred one thousand, nine hundred eighty-seven".