21544061593 has 2 divisors, whose sum is σ = 21544061594. Its totient is φ = 21544061592.

The previous prime is 21544061509. The next prime is 21544061647. The reversal of 21544061593 is 39516044512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20969356864 + 574704729 = 144808^2 + 23973^2 .

It is a cyclic number.

It is not a de Polignac number, because 21544061593 - 2⁹ = 21544061081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21544061093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772030796 + 10772030797.

It is an arithmetic number, because the mean of its divisors is an integer number (10772030797).

Almost surely, 2^21544061593 is an apocalyptic number.

It is an amenable number.

21544061593 is a deficient number, since it is larger than the sum of its proper divisors (1).

21544061593 is an equidigital number, since it uses as much as digits as its factorization.

21544061593 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 40.

The spelling of 21544061593 in words is "twenty-one billion, five hundred forty-four million, sixty-one thousand, five hundred ninety-three".