1668965521 has 2 divisors, whose sum is σ = 1668965522. Its totient is φ = 1668965520.

The previous prime is 1668965513. The next prime is 1668965527. The reversal of 1668965521 is 1255698661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1097994496 + 570971025 = 33136^2 + 23895^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668965521 - 2³ = 1668965513 is a prime.

It is not a weakly prime, because it can be changed into another prime (1668965527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834482760 + 834482761.

It is an arithmetic number, because the mean of its divisors is an integer number (834482761).

Almost surely, 2^1668965521 is an apocalyptic number.

It is an amenable number.

1668965521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668965521 is an equidigital number, since it uses as much as digits as its factorization.

1668965521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 777600, while the sum is 49.

The square root of 1668965521 is about 40852.9744449532. The cubic root of 1668965521 is about 1186.1759696980.

The spelling of 1668965521 in words is "one billion, six hundred sixty-eight million, nine hundred sixty-five thousand, five hundred twenty-one".