21261242500577 has 2 divisors, whose sum is σ = 21261242500578. Its totient is φ = 21261242500576.

The previous prime is 21261242500471. The next prime is 21261242500601. The reversal of 21261242500577 is 77500524216212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13762386033361 + 7498856467216 = 3709769^2 + 2738404^2 .

It is a cyclic number.

It is not a de Polignac number, because 21261242500577 - 2¹⁸ = 21261242238433 is a prime.

It is not a weakly prime, because it can be changed into another prime (21261242500177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10630621250288 + 10630621250289.

It is an arithmetic number, because the mean of its divisors is an integer number (10630621250289).

Almost surely, 2^{21261242500577} is an apocalyptic number.

It is an amenable number.

21261242500577 is a deficient number, since it is larger than the sum of its proper divisors (1).

21261242500577 is an equidigital number, since it uses as much as digits as its factorization.

21261242500577 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 470400, while the sum is 44.

Adding to 21261242500577 its reverse (77500524216212), we get a palindrome (98761766716789).

The spelling of 21261242500577 in words is "twenty-one trillion, two hundred sixty-one billion, two hundred forty-two million, five hundred thousand, five hundred seventy-seven".