639447 has 4 divisors (see below), whose sum is σ = 852600. Its totient is φ = 426296.

The previous prime is 639439. The next prime is 639451. The reversal of 639447 is 744936.

639447 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 639447 - 2³ = 639439 is a prime.

It is a D-number.

639447 is strictly pandigital in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639487) 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 3 ways as a sum of consecutive naturals, for example, 106572 + ... + 106577.

It is an arithmetic number, because the mean of its divisors is an integer number (213150).

2⁶³⁹⁴⁴⁷ is an apocalyptic number.

639447 is a deficient number, since it is larger than the sum of its proper divisors (213153).

639447 is a wasteful number, since it uses less digits than its factorization.

639447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213152.

The product of its digits is 18144, while the sum is 33.

The square root of 639447 is about 799.6543003073. The cubic root of 639447 is about 86.1525595659.

It can be divided in two parts, 6394 and 47, that added together give a triangular number (6441 = T₁₁₃).

The spelling of 639447 in words is "six hundred thirty-nine thousand, four hundred forty-seven".