21420388457137 has 2 divisors, whose sum is σ = 21420388457138. Its totient is φ = 21420388457136.

The previous prime is 21420388457099. The next prime is 21420388457161. The reversal of 21420388457137 is 73175488302412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21409462145296 + 10926311841 = 4627036^2 + 104529^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420388457137 - 2²⁷ = 21420254239409 is a prime.

It is not a weakly prime, because it can be changed into another prime (21420388457197) 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, 10710194228568 + 10710194228569.

It is an arithmetic number, because the mean of its divisors is an integer number (10710194228569).

Almost surely, 2^{21420388457137} is an apocalyptic number.

It is an amenable number.

21420388457137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420388457137 is an equidigital number, since it uses as much as digits as its factorization.

21420388457137 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9031680, while the sum is 55.

The spelling of 21420388457137 in words is "twenty-one trillion, four hundred twenty billion, three hundred eighty-eight million, four hundred fifty-seven thousand, one hundred thirty-seven".