639493 has 2 divisors, whose sum is σ = 639494. Its totient is φ = 639492.

The previous prime is 639491. The next prime is 639511. The reversal of 639493 is 394936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 492804 + 146689 = 702^2 + 383^2 .

It is a cyclic number.

It is not a de Polignac number, because 639493 - 2¹ = 639491 is a prime.

Together with 639491, it forms a pair of twin primes.

639493 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319746 + 319747.

It is an arithmetic number, because the mean of its divisors is an integer number (319747).

2⁶³⁹⁴⁹³ is an apocalyptic number.

It is an amenable number.

639493 is a deficient number, since it is larger than the sum of its proper divisors (1).

639493 is an equidigital number, since it uses as much as digits as its factorization.

639493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 34.

The square root of 639493 is about 799.6830622190. The cubic root of 639493 is about 86.1546253732.

The spelling of 639493 in words is "six hundred thirty-nine thousand, four hundred ninety-three".