639473 has 4 divisors (see below), whose sum is σ = 643188. Its totient is φ = 635760.

The previous prime is 639451. The next prime is 639487. The reversal of 639473 is 374936.

639473 is digitally balanced in base 2, 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 can be written as a sum of positive squares in 2 ways, for example, as 214369 + 425104 = 463^2 + 652^2 .

It is a cyclic number.

It is not a de Polignac number, because 639473 - 2¹⁸ = 377329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1586 + ... + 1947.

It is an arithmetic number, because the mean of its divisors is an integer number (160797).

2⁶³⁹⁴⁷³ is an apocalyptic number.

It is an amenable number.

639473 is a deficient number, since it is larger than the sum of its proper divisors (3715).

639473 is a wasteful number, since it uses less digits than its factorization.

639473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3714.

The product of its digits is 13608, while the sum is 32.

The square root of 639473 is about 799.6705571671. The cubic root of 639473 is about 86.1537272083.

The spelling of 639473 in words is "six hundred thirty-nine thousand, four hundred seventy-three".