21154535620481 has 2 divisors, whose sum is σ = 21154535620482. Its totient is φ = 21154535620480.

The previous prime is 21154535620447. The next prime is 21154535620597. The reversal of 21154535620481 is 18402653545112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13245166850881 + 7909368769600 = 3639391^2 + 2812360^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154535620481 - 2¹⁰ = 21154535619457 is a prime.

It is a super-2 number, since 2×21154535620481² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21154535620181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577267810240 + 10577267810241.

It is an arithmetic number, because the mean of its divisors is an integer number (10577267810241).

Almost surely, 2^{21154535620481} is an apocalyptic number.

It is an amenable number.

21154535620481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154535620481 is an equidigital number, since it uses as much as digits as its factorization.

21154535620481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152000, while the sum is 47.

The spelling of 21154535620481 in words is "twenty-one trillion, one hundred fifty-four billion, five hundred thirty-five million, six hundred twenty thousand, four hundred eighty-one".