639563893 has 2 divisors, whose sum is σ = 639563894. Its totient is φ = 639563892.

The previous prime is 639563891. The next prime is 639563923. The reversal of 639563893 is 398365936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 356718769 + 282845124 = 18887^2 + 16818^2 .

It is a cyclic number.

It is not a de Polignac number, because 639563893 - 2¹ = 639563891 is a prime.

Together with 639563891, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 639563893.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639563891) 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, 319781946 + 319781947.

It is an arithmetic number, because the mean of its divisors is an integer number (319781947).

Almost surely, 2^639563893 is an apocalyptic number.

It is an amenable number.

639563893 is a deficient number, since it is larger than the sum of its proper divisors (1).

639563893 is an equidigital number, since it uses as much as digits as its factorization.

639563893 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3149280, while the sum is 52.

The square root of 639563893 is about 25289.6004911110. The cubic root of 639563893 is about 861.5780890249.

The spelling of 639563893 in words is "six hundred thirty-nine million, five hundred sixty-three thousand, eight hundred ninety-three".