66538561087 has 4 divisors (see below), whose sum is σ = 66962373736. Its totient is φ = 66114748440.

The previous prime is 66538561043. The next prime is 66538561123. The reversal of 66538561087 is 78016583566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66538561087 - 2²⁷ = 66404343359 is a prime.

It is a super-2 number, since 2×66538561087² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66538561007) 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 in 3 ways as a sum of consecutive naturals, for example, 211906089 + ... + 211906402.

It is an arithmetic number, because the mean of its divisors is an integer number (16740593434).

Almost surely, 2^66538561087 is an apocalyptic number.

66538561087 is a deficient number, since it is larger than the sum of its proper divisors (423812649).

66538561087 is a wasteful number, since it uses less digits than its factorization.

66538561087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 423812648.

The product of its (nonzero) digits is 7257600, while the sum is 55.

The spelling of 66538561087 in words is "sixty-six billion, five hundred thirty-eight million, five hundred sixty-one thousand, eighty-seven".