1681681 has 8 divisors (see below), whose sum is σ = 1759680. Its totient is φ = 1605072.

The previous prime is 1681679. The next prime is 1681703. The reversal of 1681681 is 1861861.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1681681 - 2¹ = 1681679 is a prime.

It is a super-2 number, since 2×1681681² = 5656101971522, which contains 22 as substring.

It is a Duffinian number.

1681681 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1681621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2706 + ... + 3268.

It is an arithmetic number, because the mean of its divisors is an integer number (219960).

2^1681681 is an apocalyptic number.

It is an amenable number.

1681681 is a deficient number, since it is larger than the sum of its proper divisors (77999).

1681681 is a wasteful number, since it uses less digits than its factorization.

1681681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695.

The product of its digits is 2304, while the sum is 31.

The square root of 1681681 is about 1296.7964373794. The cubic root of 1681681 is about 118.9180755715.

It can be divided in two parts, 168 and 1681, that added together give a square (1849 = 43²).

The spelling of 1681681 in words is "one million, six hundred eighty-one thousand, six hundred eighty-one".