1681684 has 6 divisors (see below), whose sum is σ = 2942954. Its totient is φ = 840840.

The previous prime is 1681679. The next prime is 1681703. The reversal of 1681684 is 4861861.

1681684 is nontrivially palindromic in base 5.

It can be written as a sum of positive squares in only one way, i.e., 1633284 + 48400 = 1278^2 + 220^2 .

It is a super-2 number, since 2×1681684² = 5656122151712, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210207 + ... + 210214.

2^1681684 is an apocalyptic number.

It is an amenable number.

1681684 is a deficient number, since it is larger than the sum of its proper divisors (1261270).

1681684 is a wasteful number, since it uses less digits than its factorization.

1681684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 420425 (or 420423 counting only the distinct ones).

The product of its digits is 9216, while the sum is 34.

The square root of 1681684 is about 1296.7975940755. The cubic root of 1681684 is about 118.9181462853.

It can be divided in two parts, 16816 and 84, that added together give a square (16900 = 130²).

The spelling of 1681684 in words is "one million, six hundred eighty-one thousand, six hundred eighty-four".