1681665 has 8 divisors (see below), whose sum is σ = 2690688. Its totient is φ = 896880.

The previous prime is 1681661. The next prime is 1681679. The reversal of 1681665 is 5661861.

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

It is not a de Polignac number, because 1681665 - 2² = 1681661 is a prime.

1681665 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1681661) 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, 56041 + ... + 56070.

It is an arithmetic number, because the mean of its divisors is an integer number (336336).

2^1681665 is an apocalyptic number.

1681665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1681665 is a deficient number, since it is larger than the sum of its proper divisors (1009023).

1681665 is a wasteful number, since it uses less digits than its factorization.

1681665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112119.

The product of its digits is 8640, while the sum is 33.

The square root of 1681665 is about 1296.7902683164. The cubic root of 1681665 is about 118.9176984300.

It can be divided in two parts, 1681 and 665, that added together give a triangular number (2346 = T₆₈).

The spelling of 1681665 in words is "one million, six hundred eighty-one thousand, six hundred sixty-five".