1866681 has 6 divisors (see below), whose sum is σ = 2696330. Its totient is φ = 1244448.

The previous prime is 1866679. The next prime is 1866721.

1866681 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 1040400 + 826281 = 1020^2 + 909^2 .

It is not a de Polignac number, because 1866681 - 2¹ = 1866679 is a prime.

It is a super-3 number, since 3×1866681³ = 19513338385673697723, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1866281) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 103696 + ... + 103713.

2^1866681 is an apocalyptic number.

It is an amenable number.

1866681 is a deficient number, since it is larger than the sum of its proper divisors (829649).

1866681 is a wasteful number, since it uses less digits than its factorization.

1866681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207415 (or 207412 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 1866681 is about 1366.2653475808. The cubic root of 1866681 is about 123.1279651772.

The spelling of 1866681 in words is "one million, eight hundred sixty-six thousand, six hundred eighty-one".