21021841565441 has 2 divisors, whose sum is σ = 21021841565442. Its totient is φ = 21021841565440.

The previous prime is 21021841565377. The next prime is 21021841565471. The reversal of 21021841565441 is 14456514812012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20668525450225 + 353316115216 = 4546265^2 + 594404^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021841565441 - 2⁶ = 21021841565377 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021841565392 and 21021841565401.

It is not a weakly prime, because it can be changed into another prime (21021841565471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510920782720 + 10510920782721.

It is an arithmetic number, because the mean of its divisors is an integer number (10510920782721).

Almost surely, 2^{21021841565441} is an apocalyptic number.

It is an amenable number.

21021841565441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021841565441 is an equidigital number, since it uses as much as digits as its factorization.

21021841565441 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 307200, while the sum is 44.

The spelling of 21021841565441 in words is "twenty-one trillion, twenty-one billion, eight hundred forty-one million, five hundred sixty-five thousand, four hundred forty-one".