639436 has 24 divisors (see below), whose sum is σ = 1312416. Its totient is φ = 266880.

The previous prime is 639433. The next prime is 639439. The reversal of 639436 is 634936.

It is an interprime number because it is at equal distance from previous prime (639433) and next prime (639439).

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 639398 and 639407.

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 7 ways as a sum of consecutive naturals, for example, 870 + ... + 1426.

It is an arithmetic number, because the mean of its divisors is an integer number (54684).

2⁶³⁹⁴³⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (656208).

639436 is an abundant number, since it is smaller than the sum of its proper divisors (672980).

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

639436 is a wasteful number, since it uses less digits than its factorization.

639436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 609 (or 607 counting only the distinct ones).

The product of its digits is 11664, while the sum is 31.

The square root of 639436 is about 799.6474223056. The cubic root of 639436 is about 86.1520655539.

The spelling of 639436 in words is "six hundred thirty-nine thousand, four hundred thirty-six".