1685381 has 2 divisors, whose sum is σ = 1685382. Its totient is φ = 1685380.

The previous prime is 1685323. The next prime is 1685399. The reversal of 1685381 is 1835861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1069156 + 616225 = 1034^2 + 785^2 .

It is an emirp because it is prime and its reverse (1835861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1685381 - 2⁶ = 1685317 is a prime.

It is a super-2 number, since 2×1685381² = 5681018230322, which contains 22 as substring.

It is a Chen prime.

It is an Ulam number.

It is a plaindrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1685581) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842690 + 842691.

It is an arithmetic number, because the mean of its divisors is an integer number (842691).

2^1685381 is an apocalyptic number.

It is an amenable number.

1685381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685381 is an equidigital number, since it uses as much as digits as its factorization.

1685381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 32.

The square root of 1685381 is about 1298.2222459964. Note that the first 4 decimals coincide. The cubic root of 1685381 is about 119.0052253902.

The spelling of 1685381 in words is "one million, six hundred eighty-five thousand, three hundred eighty-one".