66421615525 has 6 divisors (see below), whose sum is σ = 82362803282. Its totient is φ = 53137292400.

The previous prime is 66421615493. The next prime is 66421615597. The reversal of 66421615525 is 52551612466.

It can be written as a sum of positive squares in 3 ways, for example, as 9304917444 + 57116698081 = 96462^2 + 238991^2 .

It is not a de Polignac number, because 66421615525 - 2⁵ = 66421615493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1328432286 + ... + 1328432335.

Almost surely, 2^66421615525 is an apocalyptic number.

It is an amenable number.

66421615525 is a deficient number, since it is larger than the sum of its proper divisors (15941187757).

66421615525 is a wasteful number, since it uses less digits than its factorization.

66421615525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2656864631 (or 2656864626 counting only the distinct ones).

The product of its digits is 432000, while the sum is 43.

The spelling of 66421615525 in words is "sixty-six billion, four hundred twenty-one million, six hundred fifteen thousand, five hundred twenty-five".