639757 has 2 divisors, whose sum is σ = 639758. Its totient is φ = 639756.

The previous prime is 639739. The next prime is 639833. The reversal of 639757 is 757936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 546121 + 93636 = 739^2 + 306^2 .

It is a cyclic number.

It is not a de Polignac number, because 639757 - 2¹¹ = 637709 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319878 + 319879.

It is an arithmetic number, because the mean of its divisors is an integer number (319879).

2⁶³⁹⁷⁵⁷ is an apocalyptic number.

It is an amenable number.

639757 is a deficient number, since it is larger than the sum of its proper divisors (1).

639757 is an equidigital number, since it uses as much as digits as its factorization.

639757 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 39690, while the sum is 37.

The square root of 639757 is about 799.8481105810. The cubic root of 639757 is about 86.1664793950.

The spelling of 639757 in words is "six hundred thirty-nine thousand, seven hundred fifty-seven".