1321565543653 has 2 divisors, whose sum is σ = 1321565543654. Its totient is φ = 1321565543652.

The previous prime is 1321565543651. The next prime is 1321565543677. The reversal of 1321565543653 is 3563455651231.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1301064172164 + 20501371489 = 1140642^2 + 143183^2 .

It is a cyclic number.

It is not a de Polignac number, because 1321565543653 - 2¹ = 1321565543651 is a prime.

Together with 1321565543651, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 1321565543597 and 1321565543606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1321565543651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660782771826 + 660782771827.

It is an arithmetic number, because the mean of its divisors is an integer number (660782771827).

Almost surely, 2^{1321565543653} is an apocalyptic number.

It is an amenable number.

1321565543653 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321565543653 is an equidigital number, since it uses as much as digits as its factorization.

1321565543653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4860000, while the sum is 49.

The spelling of 1321565543653 in words is "one trillion, three hundred twenty-one billion, five hundred sixty-five million, five hundred forty-three thousand, six hundred fifty-three".