1668990161 has 2 divisors, whose sum is σ = 1668990162. Its totient is φ = 1668990160.

The previous prime is 1668990137. The next prime is 1668990179. The reversal of 1668990161 is 1610998661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1651609600 + 17380561 = 40640^2 + 4169^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668990161 - 2¹⁴ = 1668973777 is a prime.

It is not a weakly prime, because it can be changed into another prime (1668992161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834495080 + 834495081.

It is an arithmetic number, because the mean of its divisors is an integer number (834495081).

Almost surely, 2^1668990161 is an apocalyptic number.

It is an amenable number.

1668990161 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668990161 is an equidigital number, since it uses as much as digits as its factorization.

1668990161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 139968, while the sum is 47.

The square root of 1668990161 is about 40853.2760130690. The cubic root of 1668990161 is about 1186.1818070928.

The spelling of 1668990161 in words is "one billion, six hundred sixty-eight million, nine hundred ninety thousand, one hundred sixty-one".