1685981 has 4 divisors (see below), whose sum is σ = 1839264. Its totient is φ = 1532700.

The previous prime is 1685977. The next prime is 1685989. The reversal of 1685981 is 1895861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1895861 = 11 ⋅172351.

It is a cyclic number.

It is not a de Polignac number, because 1685981 - 2² = 1685977 is a prime.

It is a super-2 number, since 2×1685981² = 5685063864722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1685989) 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, 76625 + ... + 76646.

It is an arithmetic number, because the mean of its divisors is an integer number (459816).

2^1685981 is an apocalyptic number.

1685981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1685981 is a deficient number, since it is larger than the sum of its proper divisors (153283).

1685981 is a wasteful number, since it uses less digits than its factorization.

1685981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153282.

The product of its digits is 17280, while the sum is 38.

The square root of 1685981 is about 1298.4533106739. The cubic root of 1685981 is about 119.0193457708.

The spelling of 1685981 in words is "one million, six hundred eighty-five thousand, nine hundred eighty-one".