1680492581 has 2 divisors, whose sum is σ = 1680492582. Its totient is φ = 1680492580.

The previous prime is 1680492557. The next prime is 1680492607. The reversal of 1680492581 is 1852940861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1680180100 + 312481 = 40990^2 + 559^2 .

It is an emirp because it is prime and its reverse (1852940861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1680492581 - 2¹⁸ = 1680230437 is a prime.

It is a super-2 number, since 2×1680492581² = 5648110629592083122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1680492521) 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, 840246290 + 840246291.

It is an arithmetic number, because the mean of its divisors is an integer number (840246291).

Almost surely, 2^1680492581 is an apocalyptic number.

It is an amenable number.

1680492581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1680492581 is an equidigital number, since it uses as much as digits as its factorization.

1680492581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 138240, while the sum is 44.

The square root of 1680492581 is about 40993.8114963710. The cubic root of 1680492581 is about 1188.9005642397.

The spelling of 1680492581 in words is "one billion, six hundred eighty million, four hundred ninety-two thousand, five hundred eighty-one".