639281 has 4 divisors (see below), whose sum is σ = 654192. Its totient is φ = 624372.

The previous prime is 639269. The next prime is 639299. The reversal of 639281 is 182936.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 639281 - 2¹⁸ = 377137 is a prime.

It is a super-2 number, since 2×639281² = 817360393922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7391 + ... + 7476.

It is an arithmetic number, because the mean of its divisors is an integer number (163548).

2⁶³⁹²⁸¹ is an apocalyptic number.

It is an amenable number.

639281 is a deficient number, since it is larger than the sum of its proper divisors (14911).

639281 is a wasteful number, since it uses less digits than its factorization.

639281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14910.

The product of its digits is 2592, while the sum is 29.

The square root of 639281 is about 799.5504987179. The cubic root of 639281 is about 86.1451038724.

The spelling of 639281 in words is "six hundred thirty-nine thousand, two hundred eighty-one".