639445 has 16 divisors (see below), whose sum is σ = 829440. Its totient is φ = 471744.

The previous prime is 639439. The next prime is 639451. The reversal of 639445 is 544936.

639445 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (639439) and next prime (639451).

It is a cyclic number.

It is not a de Polignac number, because 639445 - 2⁹ = 638933 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4972 + ... + 5098.

It is an arithmetic number, because the mean of its divisors is an integer number (51840).

2⁶³⁹⁴⁴⁵ is an apocalyptic number.

It is an amenable number.

639445 is a deficient number, since it is larger than the sum of its proper divisors (189995).

639445 is a wasteful number, since it uses less digits than its factorization.

639445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204.

The product of its digits is 12960, while the sum is 31.

The square root of 639445 is about 799.6530497660. The cubic root of 639445 is about 86.1524697460.

The spelling of 639445 in words is "six hundred thirty-nine thousand, four hundred forty-five".