639396 has 18 divisors (see below), whose sum is σ = 1616342. Its totient is φ = 213120.

The previous prime is 639391. The next prime is 639433. The reversal of 639396 is 693936.

It can be written as a sum of positive squares in only one way, i.e., 509796 + 129600 = 714^2 + 360^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 17761 = 639396 / (6 + 3 + 9 + 3 + 9 + 6).

It is a nude number because it is divisible by every one of its digits.

It is a d-powerful number, because it can be written as 6² + 3³ + 3⁷ + 9⁵ + 9⁶ + 6⁶ .

It is a self number, because there is not a number n which added to its sum of digits gives 639396.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639396.

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

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8845 + ... + 8916.

2⁶³⁹³⁹⁶ is an apocalyptic number.

It is an amenable number.

639396 is an abundant number, since it is smaller than the sum of its proper divisors (976946).

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

639396 is a wasteful number, since it uses less digits than its factorization.

639396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17771 (or 17766 counting only the distinct ones).

The product of its digits is 26244, while the sum is 36.

The square root of 639396 is about 799.6224108915. The cubic root of 639396 is about 86.1502690986.

It can be divided in two parts, 639 and 396, that added together give a triangular number (1035 = T₄₅).

The spelling of 639396 in words is "six hundred thirty-nine thousand, three hundred ninety-six".