1687381 has 2 divisors, whose sum is σ = 1687382. Its totient is φ = 1687380.

The previous prime is 1687373. The next prime is 1687393. The reversal of 1687381 is 1837861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 980100 + 707281 = 990^2 + 841^2 .

It is a cyclic number.

It is not a de Polignac number, because 1687381 - 2³ = 1687373 is a prime.

It is a super-2 number, since 2×1687381² = 5694509278322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1687331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 843690 + 843691.

It is an arithmetic number, because the mean of its divisors is an integer number (843691).

2^1687381 is an apocalyptic number.

It is an amenable number.

1687381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1687381 is an equidigital number, since it uses as much as digits as its factorization.

1687381 is an evil number, because the sum of its binary digits is even.

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

The square root of 1687381 is about 1298.9923017478. The cubic root of 1687381 is about 119.0522803026.

The spelling of 1687381 in words is "one million, six hundred eighty-seven thousand, three hundred eighty-one".