1320813661 has 2 divisors, whose sum is σ = 1320813662. Its totient is φ = 1320813660.

The previous prime is 1320813607. The next prime is 1320813673. The reversal of 1320813661 is 1663180231.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1083068100 + 237745561 = 32910^2 + 15419^2 .

It is a cyclic number.

It is not a de Polignac number, because 1320813661 - 2¹⁷ = 1320682589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1320814661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660406830 + 660406831.

It is an arithmetic number, because the mean of its divisors is an integer number (660406831).

Almost surely, 2^1320813661 is an apocalyptic number.

It is an amenable number.

1320813661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1320813661 is an equidigital number, since it uses as much as digits as its factorization.

1320813661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 1320813661 is about 36343.0001650937. Note that the first 3 decimals coincide. The cubic root of 1320813661 is about 1097.1866567760.

Adding to 1320813661 its reverse (1663180231), we get a palindrome (2983993892).

The spelling of 1320813661 in words is "one billion, three hundred twenty million, eight hundred thirteen thousand, six hundred sixty-one".