639317281 has 2 divisors, whose sum is σ = 639317282. Its totient is φ = 639317280.

The previous prime is 639317279. The next prime is 639317297. The reversal of 639317281 is 182713936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 367067281 + 272250000 = 19159^2 + 16500^2 .

It is a cyclic number.

It is not a de Polignac number, because 639317281 - 2¹ = 639317279 is a prime.

It is a super-2 number, since 2×639317281² = 817453171570465922, which contains 22 as substring.

Together with 639317279, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (639317201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319658640 + 319658641.

It is an arithmetic number, because the mean of its divisors is an integer number (319658641).

Almost surely, 2^639317281 is an apocalyptic number.

It is an amenable number.

639317281 is a deficient number, since it is larger than the sum of its proper divisors (1).

639317281 is an equidigital number, since it uses as much as digits as its factorization.

639317281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 40.

The square root of 639317281 is about 25284.7242618938. The cubic root of 639317281 is about 861.4673350076.

The spelling of 639317281 in words is "six hundred thirty-nine million, three hundred seventeen thousand, two hundred eighty-one".