641647987 has 2 divisors, whose sum is σ = 641647988. Its totient is φ = 641647986.

The previous prime is 641647913. The next prime is 641647999. The reversal of 641647987 is 789746146.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-641647987 is a prime.

It is not a weakly prime, because it can be changed into another prime (641647907) 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, 320823993 + 320823994.

It is an arithmetic number, because the mean of its divisors is an integer number (320823994).

Almost surely, 2^641647987 is an apocalyptic number.

641647987 is a deficient number, since it is larger than the sum of its proper divisors (1).

641647987 is an equidigital number, since it uses as much as digits as its factorization.

641647987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2032128, while the sum is 52.

The square root of 641647987 is about 25330.7715437173. The cubic root of 641647987 is about 862.5129254382.

The spelling of 641647987 in words is "six hundred forty-one million, six hundred forty-seven thousand, nine hundred eighty-seven".