671643 has 18 divisors (see below), whose sum is σ = 1129284. Its totient is φ = 383544.

The previous prime is 671633. The next prime is 671647. The reversal of 671643 is 346176.

It is not a de Polignac number, because 671643 - 2⁹ = 671131 is a prime.

It is a super-2 number, since 2×671643² = 902208638898, which contains 22 as substring.

671643 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (671647) 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 17 ways as a sum of consecutive naturals, for example, 321 + ... + 1202.

It is an arithmetic number, because the mean of its divisors is an integer number (62738).

2⁶⁷¹⁶⁴³ is an apocalyptic number.

671643 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

671643 is a deficient number, since it is larger than the sum of its proper divisors (457641).

671643 is a wasteful number, since it uses less digits than its factorization.

671643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1543 (or 1533 counting only the distinct ones).

The product of its digits is 3024, while the sum is 27.

The square root of 671643 is about 819.5382846457. The cubic root of 671643 is about 87.5748692533.

The spelling of 671643 in words is "six hundred seventy-one thousand, six hundred forty-three".