21042451055513 has 2 divisors, whose sum is σ = 21042451055514. Its totient is φ = 21042451055512.

The previous prime is 21042451055501. The next prime is 21042451055623. The reversal of 21042451055513 is 31555015424012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13376048099584 + 7666402955929 = 3657328^2 + 2768827^2 .

It is a cyclic number.

It is not a de Polignac number, because 21042451055513 - 2³⁴ = 21025271186329 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21042451055713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521225527756 + 10521225527757.

It is an arithmetic number, because the mean of its divisors is an integer number (10521225527757).

Almost surely, 2^{21042451055513} is an apocalyptic number.

It is an amenable number.

21042451055513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042451055513 is an equidigital number, since it uses as much as digits as its factorization.

21042451055513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120000, while the sum is 38.

Adding to 21042451055513 its reverse (31555015424012), we get a palindrome (52597466479525).

The spelling of 21042451055513 in words is "twenty-one trillion, forty-two billion, four hundred fifty-one million, fifty-five thousand, five hundred thirteen".