20437565521 has 2 divisors, whose sum is σ = 20437565522. Its totient is φ = 20437565520.

The previous prime is 20437565453. The next prime is 20437565527. The reversal of 20437565521 is 12556573402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10782537921 + 9655027600 = 103839^2 + 98260^2 .

It is a cyclic number.

It is not a de Polignac number, because 20437565521 - 2¹¹ = 20437563473 is a prime.

It is not a weakly prime, because it can be changed into another prime (20437565527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10218782760 + 10218782761.

It is an arithmetic number, because the mean of its divisors is an integer number (10218782761).

Almost surely, 2^20437565521 is an apocalyptic number.

It is an amenable number.

20437565521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20437565521 is an equidigital number, since it uses as much as digits as its factorization.

20437565521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252000, while the sum is 40.

The spelling of 20437565521 in words is "twenty billion, four hundred thirty-seven million, five hundred sixty-five thousand, five hundred twenty-one".