21653063565421 has 2 divisors, whose sum is σ = 21653063565422. Its totient is φ = 21653063565420.

The previous prime is 21653063565409. The next prime is 21653063565487. The reversal of 21653063565421 is 12456536035612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20837809874025 + 815253691396 = 4564845^2 + 902914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21653063565421 - 2¹⁷ = 21653063434349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21653063560421) 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, 10826531782710 + 10826531782711.

It is an arithmetic number, because the mean of its divisors is an integer number (10826531782711).

Almost surely, 2^{21653063565421} is an apocalyptic number.

It is an amenable number.

21653063565421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21653063565421 is an equidigital number, since it uses as much as digits as its factorization.

21653063565421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888000, while the sum is 49.

The spelling of 21653063565421 in words is "twenty-one trillion, six hundred fifty-three billion, sixty-three million, five hundred sixty-five thousand, four hundred twenty-one".