639009 has 40 divisors (see below), whose sum is σ = 1161600. Its totient is φ = 349272.

The previous prime is 639007. The next prime is 639011. The reversal of 639009 is 900936.

It is an interprime number because it is at equal distance from previous prime (639007) and next prime (639011).

It is not a de Polignac number, because 639009 - 2¹ = 639007 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639007) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 27772 + ... + 27794.

It is an arithmetic number, because the mean of its divisors is an integer number (29040).

2⁶³⁹⁰⁰⁹ is an apocalyptic number.

639009 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

It is an amenable number.

639009 is a deficient number, since it is larger than the sum of its proper divisors (522591).

639009 is an equidigital number, since it uses as much as digits as its factorization.

639009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56 (or 33 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 27.

The square root of 639009 is about 799.3803850483. The cubic root of 639009 is about 86.1328845237.

The spelling of 639009 in words is "six hundred thirty-nine thousand, nine".