13538456021 has 2 divisors, whose sum is σ = 13538456022. Its totient is φ = 13538456020.

The previous prime is 13538456017. The next prime is 13538456111. The reversal of 13538456021 is 12065483531.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8678971921 + 4859484100 = 93161^2 + 69710^2 .

It is a cyclic number.

It is not a de Polignac number, because 13538456021 - 2² = 13538456017 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13538456011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6769228010 + 6769228011.

It is an arithmetic number, because the mean of its divisors is an integer number (6769228011).

Almost surely, 2^13538456021 is an apocalyptic number.

It is an amenable number.

13538456021 is a deficient number, since it is larger than the sum of its proper divisors (1).

13538456021 is an equidigital number, since it uses as much as digits as its factorization.

13538456021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 86400, while the sum is 38.

The spelling of 13538456021 in words is "thirteen billion, five hundred thirty-eight million, four hundred fifty-six thousand, twenty-one".