1690985 has 4 divisors (see below), whose sum is σ = 2029188. Its totient is φ = 1352784.

The previous prime is 1690967. The next prime is 1690993. The reversal of 1690985 is 5890961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5890961 = 31 ⋅190031.

It can be written as a sum of positive squares in 2 ways, for example, as 839056 + 851929 = 916^2 + 923^2 .

It is a cyclic number.

It is not a de Polignac number, because 1690985 - 2¹⁴ = 1674601 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 169094 + ... + 169103.

It is an arithmetic number, because the mean of its divisors is an integer number (507297).

2^1690985 is an apocalyptic number.

It is an amenable number.

1690985 is a deficient number, since it is larger than the sum of its proper divisors (338203).

1690985 is an equidigital number, since it uses as much as digits as its factorization.

1690985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338202.

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 1690985 is about 1300.3787909682. The cubic root of 1690985 is about 119.1369794719.

The spelling of 1690985 in words is "one million, six hundred ninety thousand, nine hundred eighty-five".