639245 has 4 divisors (see below), whose sum is σ = 767100. Its totient is φ = 511392.

The previous prime is 639211. The next prime is 639253. The reversal of 639245 is 542936.

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 481636 + 157609 = 694^2 + 397^2 .

It is a cyclic number.

It is not a de Polignac number, because 639245 - 2⁶ = 639181 is a prime.

It is a d-powerful number, because it can be written as 6² + 3⁹ + 2¹⁹ + 9³ + 4⁷ + 5⁷ .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63920 + ... + 63929.

It is an arithmetic number, because the mean of its divisors is an integer number (191775).

2⁶³⁹²⁴⁵ is an apocalyptic number.

It is an amenable number.

639245 is a deficient number, since it is larger than the sum of its proper divisors (127855).

639245 is a wasteful number, since it uses less digits than its factorization.

639245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127854.

The product of its digits is 6480, while the sum is 29.

The square root of 639245 is about 799.5279857516. The cubic root of 639245 is about 86.1434868047.

The spelling of 639245 in words is "six hundred thirty-nine thousand, two hundred forty-five".