669191987 has 2 divisors, whose sum is σ = 669191988. Its totient is φ = 669191986.

The previous prime is 669191977. The next prime is 669192011. The reversal of 669191987 is 789191966.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 669191987 - 2¹² = 669187891 is a prime.

It is not a weakly prime, because it can be changed into another prime (669191917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334595993 + 334595994.

It is an arithmetic number, because the mean of its divisors is an integer number (334595994).

Almost surely, 2^669191987 is an apocalyptic number.

669191987 is a deficient number, since it is larger than the sum of its proper divisors (1).

669191987 is an equidigital number, since it uses as much as digits as its factorization.

669191987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1469664, while the sum is 56.

The square root of 669191987 is about 25868.7453696541. The cubic root of 669191987 is about 874.6821101564.

The spelling of 669191987 in words is "six hundred sixty-nine million, one hundred ninety-one thousand, nine hundred eighty-seven".