1678661 has 4 divisors (see below), whose sum is σ = 1691052. Its totient is φ = 1666272.

The previous prime is 1678657. The next prime is 1678673. The reversal of 1678661 is 1668761.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1668761 = 31 ⋅53831.

It can be written as a sum of positive squares in 2 ways, for example, as 902500 + 776161 = 950^2 + 881^2 .

It is a cyclic number.

It is not a de Polignac number, because 1678661 - 2² = 1678657 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1678601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5990 + ... + 6263.

It is an arithmetic number, because the mean of its divisors is an integer number (422763).

2^1678661 is an apocalyptic number.

It is an amenable number.

1678661 is a deficient number, since it is larger than the sum of its proper divisors (12391).

1678661 is a wasteful number, since it uses less digits than its factorization.

1678661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12390.

The product of its digits is 12096, while the sum is 35.

The square root of 1678661 is about 1295.6315062548. The cubic root of 1678661 is about 118.8468476786.

The spelling of 1678661 in words is "one million, six hundred seventy-eight thousand, six hundred sixty-one".