21506065664453 has 2 divisors, whose sum is σ = 21506065664454. Its totient is φ = 21506065664452.

The previous prime is 21506065664443. The next prime is 21506065664467. The reversal of 21506065664453 is 35446656060512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17838813854404 + 3667251810049 = 4223602^2 + 1915007^2 .

It is a cyclic number.

It is not a de Polignac number, because 21506065664453 - 2⁴ = 21506065664437 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21506065664395 and 21506065664404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21506065664443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753032832226 + 10753032832227.

It is an arithmetic number, because the mean of its divisors is an integer number (10753032832227).

Almost surely, 2^{21506065664453} is an apocalyptic number.

It is an amenable number.

21506065664453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506065664453 is an equidigital number, since it uses as much as digits as its factorization.

21506065664453 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552000, while the sum is 53.

The spelling of 21506065664453 in words is "twenty-one trillion, five hundred six billion, sixty-five million, six hundred sixty-four thousand, four hundred fifty-three".