639695 has 16 divisors (see below), whose sum is σ = 897600. Its totient is φ = 437472.

The previous prime is 639689. The next prime is 639697. The reversal of 639695 is 596936.

It is not a de Polignac number, because 639695 - 2⁴ = 639679 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1529 + ... + 1901.

It is an arithmetic number, because the mean of its divisors is an integer number (56100).

2⁶³⁹⁶⁹⁵ is an apocalyptic number.

639695 is a deficient number, since it is larger than the sum of its proper divisors (257905).

639695 is an equidigital number, since it uses as much as digits as its factorization.

639695 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399 (or 385 counting only the distinct ones).

The product of its digits is 43740, while the sum is 38.

The square root of 639695 is about 799.8093522834. The cubic root of 639695 is about 86.1636957890.

The spelling of 639695 in words is "six hundred thirty-nine thousand, six hundred ninety-five".