1668336521 has 2 divisors, whose sum is σ = 1668336522. Its totient is φ = 1668336520.

The previous prime is 1668336511. The next prime is 1668336557. The reversal of 1668336521 is 1256338661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1036518025 + 631818496 = 32195^2 + 25136^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668336521 - 2¹⁸ = 1668074377 is a prime.

It is not a weakly prime, because it can be changed into another prime (1668336511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834168260 + 834168261.

It is an arithmetic number, because the mean of its divisors is an integer number (834168261).

Almost surely, 2^1668336521 is an apocalyptic number.

It is an amenable number.

1668336521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668336521 is an equidigital number, since it uses as much as digits as its factorization.

1668336521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 155520, while the sum is 41.

The square root of 1668336521 is about 40845.2753816154. The cubic root of 1668336521 is about 1186.0269355756.

The spelling of 1668336521 in words is "one billion, six hundred sixty-eight million, three hundred thirty-six thousand, five hundred twenty-one".