1690081 has 2 divisors, whose sum is σ = 1690082. Its totient is φ = 1690080.

The previous prime is 1690079. The next prime is 1690097. The reversal of 1690081 is 1800961.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1690000 + 81 = 1300^2 + 9^2 .

It is an emirp because it is prime and its reverse (1800961) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1690081 - 2¹ = 1690079 is a prime.

It is a super-2 number, since 2×1690081² = 5712747573122, which contains 22 as substring.

Together with 1690079, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1690681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 845040 + 845041.

It is an arithmetic number, because the mean of its divisors is an integer number (845041).

2^1690081 is an apocalyptic number.

It is an amenable number.

1690081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1690081 is an equidigital number, since it uses as much as digits as its factorization.

1690081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 1690081 is about 1300.0311534729. The cubic root of 1690081 is about 119.1157454915.

It can be divided in two parts, 16900 and 81, that multiplied together give a square (1368900 = 1170²).

The spelling of 1690081 in words is "one million, six hundred ninety thousand, eighty-one".