1321512604561 has 2 divisors, whose sum is σ = 1321512604562. Its totient is φ = 1321512604560.

The previous prime is 1321512604519. The next prime is 1321512604583. The reversal of 1321512604561 is 1654062151231.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1320474476161 + 1038128400 = 1149119^2 + 32220^2 .

It is a cyclic number.

It is not a de Polignac number, because 1321512604561 - 2¹¹ = 1321512602513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1321512604561.

It is not a weakly prime, because it can be changed into another prime (1321512604501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660756302280 + 660756302281.

It is an arithmetic number, because the mean of its divisors is an integer number (660756302281).

Almost surely, 2^{1321512604561} is an apocalyptic number.

It is an amenable number.

1321512604561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321512604561 is an equidigital number, since it uses as much as digits as its factorization.

1321512604561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43200, while the sum is 37.

Adding to 1321512604561 its reverse (1654062151231), we get a palindrome (2975574755792).

It can be divided in two parts, 13215 and 12604561, that added together give a triangular number (12617776 = T₅₀₂₃).

The spelling of 1321512604561 in words is "one trillion, three hundred twenty-one billion, five hundred twelve million, six hundred four thousand, five hundred sixty-one".