1681642 has 4 divisors (see below), whose sum is σ = 2522466. Its totient is φ = 840820.

The previous prime is 1681639. The next prime is 1681649. The reversal of 1681642 is 2461861.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1461681 + 219961 = 1209^2 + 469^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1681642.

It is not an unprimeable number, because it can be changed into a prime (1681649) 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 as a sum of consecutive naturals, namely, 420409 + ... + 420412.

2^1681642 is an apocalyptic number.

1681642 is a deficient number, since it is larger than the sum of its proper divisors (840824).

1681642 is an equidigital number, since it uses as much as digits as its factorization.

1681642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 840823.

The product of its digits is 2304, while the sum is 28.

The square root of 1681642 is about 1296.7814002368. The cubic root of 1681642 is about 118.9171562848.

The spelling of 1681642 in words is "one million, six hundred eighty-one thousand, six hundred forty-two".