639873 has 16 divisors (see below), whose sum is σ = 1021440. Its totient is φ = 393552.

The previous prime is 639857. The next prime is 639907. The reversal of 639873 is 378936.

It is not a de Polignac number, because 639873 - 2⁴ = 639857 is a prime.

It is a super-2 number, since 2×639873² = 818874912258, which contains 22 as substring.

639873 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (639833) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 561 + ... + 1262.

It is an arithmetic number, because the mean of its divisors is an integer number (63840).

2⁶³⁹⁸⁷³ is an apocalyptic number.

It is an amenable number.

639873 is a deficient number, since it is larger than the sum of its proper divisors (381567).

639873 is a wasteful number, since it uses less digits than its factorization.

639873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1845 (or 1839 counting only the distinct ones).

The product of its digits is 27216, while the sum is 36.

The square root of 639873 is about 799.9206210619. The cubic root of 639873 is about 86.1716869491.

The spelling of 639873 in words is "six hundred thirty-nine thousand, eight hundred seventy-three".