661671 has 12 divisors (see below), whose sum is σ = 982072. Its totient is φ = 428976.

The previous prime is 661663. The next prime is 661673. The reversal of 661671 is 176166.

It is not a de Polignac number, because 661671 - 2³ = 661663 is a prime.

It is a Duffinian number.

661671 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661673) 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, 661 + ... + 1326.

2⁶⁶¹⁶⁷¹ is an apocalyptic number.

661671 is a deficient number, since it is larger than the sum of its proper divisors (320401).

661671 is a wasteful number, since it uses less digits than its factorization.

661671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2030 (or 2027 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 661671 is about 813.4316197444. The cubic root of 661671 is about 87.1392933110.

The spelling of 661671 in words is "six hundred sixty-one thousand, six hundred seventy-one".