639886739 has 2 divisors, whose sum is σ = 639886740. Its totient is φ = 639886738.

The previous prime is 639886727. The next prime is 639886747. The reversal of 639886739 is 937688936.

639886739 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 639886739 - 2¹² = 639882643 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (639886439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319943369 + 319943370.

It is an arithmetic number, because the mean of its divisors is an integer number (319943370).

Almost surely, 2^639886739 is an apocalyptic number.

639886739 is a deficient number, since it is larger than the sum of its proper divisors (1).

639886739 is an equidigital number, since it uses as much as digits as its factorization.

639886739 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11757312, while the sum is 59.

The square root of 639886739 is about 25295.9826652376. The cubic root of 639886739 is about 861.7230368829.

The spelling of 639886739 in words is "six hundred thirty-nine million, eight hundred eighty-six thousand, seven hundred thirty-nine".