638168647 has 2 divisors, whose sum is σ = 638168648. Its totient is φ = 638168646.

The previous prime is 638168617. The next prime is 638168659. The reversal of 638168647 is 746861836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638168647 - 2¹⁵ = 638135879 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638168647.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638168617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319084323 + 319084324.

It is an arithmetic number, because the mean of its divisors is an integer number (319084324).

Almost surely, 2^638168647 is an apocalyptic number.

638168647 is a deficient number, since it is larger than the sum of its proper divisors (1).

638168647 is an equidigital number, since it uses as much as digits as its factorization.

638168647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1161216, while the sum is 49.

The square root of 638168647 is about 25262.0000593777. Note that the first 4 decimals coincide. The cubic root of 638168647 is about 860.9511052229.

The spelling of 638168647 in words is "six hundred thirty-eight million, one hundred sixty-eight thousand, six hundred forty-seven".