665801671 has 8 divisors (see below), whose sum is σ = 680439744. Its totient is φ = 651183360.

The previous prime is 665801657. The next prime is 665801687. The reversal of 665801671 is 176108566.

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

It is a cyclic number.

It is not a de Polignac number, because 665801671 - 2⁹ = 665801159 is a prime.

It is a super-3 number, since 3×665801671³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665801611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78351 + ... + 86431.

It is an arithmetic number, because the mean of its divisors is an integer number (85054968).

Almost surely, 2^665801671 is an apocalyptic number.

665801671 is a deficient number, since it is larger than the sum of its proper divisors (14638073).

665801671 is a wasteful number, since it uses less digits than its factorization.

665801671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9881.

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 665801671 is about 25803.1329686920. The cubic root of 665801671 is about 873.2024795531.

The spelling of 665801671 in words is "six hundred sixty-five million, eight hundred one thousand, six hundred seventy-one".