639427 has 4 divisors (see below), whose sum is σ = 641080. Its totient is φ = 637776.

The previous prime is 639391. The next prime is 639433. The reversal of 639427 is 724936.

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 639427 - 2⁷ = 639299 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639487) 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, 103 + ... + 1135.

It is an arithmetic number, because the mean of its divisors is an integer number (160270).

2⁶³⁹⁴²⁷ is an apocalyptic number.

639427 is a deficient number, since it is larger than the sum of its proper divisors (1653).

639427 is a wasteful number, since it uses less digits than its factorization.

639427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1652.

The product of its digits is 9072, while the sum is 31.

The square root of 639427 is about 799.6417948056. The cubic root of 639427 is about 86.1516613580.

The spelling of 639427 in words is "six hundred thirty-nine thousand, four hundred twenty-seven".