671808861 has 12 divisors (see below), whose sum is σ = 971010300. Its totient is φ = 447586560.

The previous prime is 671808847. The next prime is 671808871. The reversal of 671808861 is 168808176.

It can be written as a sum of positive squares in 2 ways, for example, as 208224900 + 463583961 = 14430^2 + 21531^2 .

It is not a de Polignac number, because 671808861 - 2⁷ = 671808733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (671808871) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8436 + ... + 37613.

It is an arithmetic number, because the mean of its divisors is an integer number (80917525).

Almost surely, 2^671808861 is an apocalyptic number.

It is an amenable number.

671808861 is a deficient number, since it is larger than the sum of its proper divisors (299201439).

671808861 is a wasteful number, since it uses less digits than its factorization.

671808861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47676 (or 47673 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 671808861 is about 25919.2758579402. The cubic root of 671808861 is about 875.8207747745.

The spelling of 671808861 in words is "six hundred seventy-one million, eight hundred eight thousand, eight hundred sixty-one".