21365512127137 has 2 divisors, whose sum is σ = 21365512127138. Its totient is φ = 21365512127136.

The previous prime is 21365512127053. The next prime is 21365512127147. The reversal of 21365512127137 is 73172121556312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21016439128161 + 349072998976 = 4584369^2 + 590824^2 .

It is a cyclic number.

It is not a de Polignac number, because 21365512127137 - 2³⁹ = 20815756313249 is a prime.

It is not a weakly prime, because it can be changed into another prime (21365512127147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682756063568 + 10682756063569.

It is an arithmetic number, because the mean of its divisors is an integer number (10682756063569).

Almost surely, 2^{21365512127137} is an apocalyptic number.

It is an amenable number.

21365512127137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21365512127137 is an equidigital number, since it uses as much as digits as its factorization.

21365512127137 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 529200, while the sum is 46.

The spelling of 21365512127137 in words is "twenty-one trillion, three hundred sixty-five billion, five hundred twelve million, one hundred twenty-seven thousand, one hundred thirty-seven".