1320644657 has 2 divisors, whose sum is σ = 1320644658. Its totient is φ = 1320644656.

The previous prime is 1320644627. The next prime is 1320644669. The reversal of 1320644657 is 7564460231.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1278706081 + 41938576 = 35759^2 + 6476^2 .

It is an emirp because it is prime and its reverse (7564460231) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1320644657 - 2⁸ = 1320644401 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1320644657.

It is not a weakly prime, because it can be changed into another prime (1320644617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660322328 + 660322329.

It is an arithmetic number, because the mean of its divisors is an integer number (660322329).

Almost surely, 2^1320644657 is an apocalyptic number.

It is an amenable number.

1320644657 is a deficient number, since it is larger than the sum of its proper divisors (1).

1320644657 is an equidigital number, since it uses as much as digits as its factorization.

1320644657 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120960, while the sum is 38.

The square root of 1320644657 is about 36340.6749662138. The cubic root of 1320644657 is about 1097.1398581375.

The spelling of 1320644657 in words is "one billion, three hundred twenty million, six hundred forty-four thousand, six hundred fifty-seven".