671639 has 4 divisors (see below), whose sum is σ = 678024. Its totient is φ = 665256.

The previous prime is 671633. The next prime is 671647. The reversal of 671639 is 936176.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 671639 - 2⁸ = 671383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (671633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3032 + ... + 3245.

It is an arithmetic number, because the mean of its divisors is an integer number (169506).

2⁶⁷¹⁶³⁹ is an apocalyptic number.

671639 is a deficient number, since it is larger than the sum of its proper divisors (6385).

671639 is a wasteful number, since it uses less digits than its factorization.

671639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6384.

The product of its digits is 6804, while the sum is 32.

The square root of 671639 is about 819.5358442436. The cubic root of 671639 is about 87.5746954009.

The spelling of 671639 in words is "six hundred seventy-one thousand, six hundred thirty-nine".