21525984637 has 2 divisors, whose sum is σ = 21525984638. Its totient is φ = 21525984636.

The previous prime is 21525984619. The next prime is 21525984643. The reversal of 21525984637 is 73648952512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11665296036 + 9860688601 = 108006^2 + 99301^2 .

It is a cyclic number.

It is not a de Polignac number, because 21525984637 - 2³¹ = 19378500989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21525984677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10762992318 + 10762992319.

It is an arithmetic number, because the mean of its divisors is an integer number (10762992319).

Almost surely, 2^21525984637 is an apocalyptic number.

It is an amenable number.

21525984637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21525984637 is an equidigital number, since it uses as much as digits as its factorization.

21525984637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3628800, while the sum is 52.

The spelling of 21525984637 in words is "twenty-one billion, five hundred twenty-five million, nine hundred eighty-four thousand, six hundred thirty-seven".