661684 has 12 divisors (see below), whose sum is σ = 1185184. Its totient is φ = 323064.

The previous prime is 661679. The next prime is 661697. The reversal of 661684 is 486166.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1752 + ... + 2095.

2⁶⁶¹⁶⁸⁴ is an apocalyptic number.

It is an amenable number.

661684 is a deficient number, since it is larger than the sum of its proper divisors (523500).

661684 is a wasteful number, since it uses less digits than its factorization.

661684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3894 (or 3892 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 661684 is about 813.4396105428. The cubic root of 661684 is about 87.1398639890.

The spelling of 661684 in words is "six hundred sixty-one thousand, six hundred eighty-four".