671861 has 4 divisors (see below), whose sum is σ = 679500. Its totient is φ = 664224.

The previous prime is 671851. The next prime is 671887. The reversal of 671861 is 168176.

671861 = 39² + 40² + ... + 127².

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

It can be written as a sum of positive squares in 2 ways, for example, as 348100 + 323761 = 590^2 + 569^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-671861 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 6.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (671831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3686 + ... + 3863.

It is an arithmetic number, because the mean of its divisors is an integer number (169875).

2⁶⁷¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

671861 is a deficient number, since it is larger than the sum of its proper divisors (7639).

671861 is an equidigital number, since it uses as much as digits as its factorization.

671861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7638.

The product of its digits is 2016, while the sum is 29.

The square root of 671861 is about 819.6712755733. The cubic root of 671861 is about 87.5843431635.

The spelling of 671861 in words is "six hundred seventy-one thousand, eight hundred sixty-one".