671638 has 8 divisors (see below), whose sum is σ = 1099080. Its totient is φ = 305280.

The previous prime is 671633. The next prime is 671647. The reversal of 671638 is 836176.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

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

671638 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15243 + ... + 15286.

It is an arithmetic number, because the mean of its divisors is an integer number (137385).

2⁶⁷¹⁶³⁸ is an apocalyptic number.

671638 is a deficient number, since it is larger than the sum of its proper divisors (427442).

671638 is a wasteful number, since it uses less digits than its factorization.

671638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30542.

The product of its digits is 6048, while the sum is 31.

The square root of 671638 is about 819.5352341419. The cubic root of 671638 is about 87.5746519377.

It can be divided in two parts, 67 and 1638, that multiplied together give a triangular number (109746 = T₄₆₈).

The spelling of 671638 in words is "six hundred seventy-one thousand, six hundred thirty-eight".