1681387 has 4 divisors (see below), whose sum is σ = 1691280. Its totient is φ = 1671496.

The previous prime is 1681363. The next prime is 1681397. The reversal of 1681387 is 7831861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7831861 = 41 ⋅191021.

It is a cyclic number.

It is not a de Polignac number, because 1681387 - 2⁷ = 1681259 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1681307) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4687 + ... + 5032.

It is an arithmetic number, because the mean of its divisors is an integer number (422820).

2^1681387 is an apocalyptic number.

1681387 is a deficient number, since it is larger than the sum of its proper divisors (9893).

1681387 is an equidigital number, since it uses as much as digits as its factorization.

1681387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9892.

The product of its digits is 8064, while the sum is 34.

The square root of 1681387 is about 1296.6830761601. The cubic root of 1681387 is about 118.9111452140.

It can be divided in two parts, 16813 and 87, that added together give a square (16900 = 130²).

The spelling of 1681387 in words is "one million, six hundred eighty-one thousand, three hundred eighty-seven".