639390 has 16 divisors (see below), whose sum is σ = 1534608. Its totient is φ = 170496.

The previous prime is 639371. The next prime is 639391. The reversal of 639390 is 93936.

639390 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 21313 = 639390 / (6 + 3 + 9 + 3 + 9 + 0).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639391) by changing a digit.

639390 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10627 + ... + 10686.

It is an arithmetic number, because the mean of its divisors is an integer number (95913).

2⁶³⁹³⁹⁰ is an apocalyptic number.

639390 is an abundant number, since it is smaller than the sum of its proper divisors (895218).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639390 is a wasteful number, since it uses less digits than its factorization.

639390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21323.

The product of its (nonzero) digits is 4374, while the sum is 30.

The square root of 639390 is about 799.6186591120. The cubic root of 639390 is about 86.1499996239.

It can be divided in two parts, 63 and 9390, that added together give a triangular number (9453 = T₁₃₇).

The spelling of 639390 in words is "six hundred thirty-nine thousand, three hundred ninety".