1621513046561 has 2 divisors, whose sum is σ = 1621513046562. Its totient is φ = 1621513046560.

The previous prime is 1621513046383. The next prime is 1621513046597. The reversal of 1621513046561 is 1656403151261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1352001515536 + 269511531025 = 1162756^2 + 519145^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621513046561 - 2³⁸ = 1346635139617 is a prime.

It is not a weakly prime, because it can be changed into another prime (1621513046161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810756523280 + 810756523281.

It is an arithmetic number, because the mean of its divisors is an integer number (810756523281).

Almost surely, 2^{1621513046561} is an apocalyptic number.

It is an amenable number.

1621513046561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621513046561 is an equidigital number, since it uses as much as digits as its factorization.

1621513046561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 129600, while the sum is 41.

The spelling of 1621513046561 in words is "one trillion, six hundred twenty-one billion, five hundred thirteen million, forty-six thousand, five hundred sixty-one".