671649 has 8 divisors (see below), whose sum is σ = 976992. Its totient is φ = 407040.

The previous prime is 671647. The next prime is 671651. The reversal of 671649 is 946176.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (671647) and next prime (671651).

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

It is not a de Polignac number, because 671649 - 2¹ = 671647 is a prime.

It is a super-2 number, since 2×671649² = 902224758402, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 20353 = 671649 / (6 + 7 + 1 + 6 + 4 + 9).

It is a Curzon number.

It is a plaindrome in base 14.

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 (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10144 + ... + 10209.

It is an arithmetic number, because the mean of its divisors is an integer number (122124).

2⁶⁷¹⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

671649 is a deficient number, since it is larger than the sum of its proper divisors (305343).

671649 is a wasteful number, since it uses less digits than its factorization.

671649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20367.

The product of its digits is 9072, while the sum is 33.

The square root of 671649 is about 819.5419452353. The cubic root of 671649 is about 87.5751300305.

The spelling of 671649 in words is "six hundred seventy-one thousand, six hundred forty-nine".