1681646 has 4 divisors (see below), whose sum is σ = 2522472. Its totient is φ = 840822.

The previous prime is 1681639. The next prime is 1681649. The reversal of 1681646 is 6461861.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6461861 = 7 ⋅923123.

It is a d-powerful number, because it can be written as 1 + 6³ + 8³ + 1 + 6⁴ + 4 + 6⁸ .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420410 + ... + 420413.

It is an arithmetic number, because the mean of its divisors is an integer number (630618).

2^1681646 is an apocalyptic number.

1681646 is a deficient number, since it is larger than the sum of its proper divisors (840826).

1681646 is an equidigital number, since it uses as much as digits as its factorization.

1681646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 840825.

The product of its digits is 6912, while the sum is 32.

The square root of 1681646 is about 1296.7829425158. The cubic root of 1681646 is about 118.9172505713.

The spelling of 1681646 in words is "one million, six hundred eighty-one thousand, six hundred forty-six".