66868626521 has 4 divisors (see below), whose sum is σ = 66869171712. Its totient is φ = 66868081332.

The previous prime is 66868626497. The next prime is 66868626527. The reversal of 66868626521 is 12562686866.

66868626521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12562686866 = 2 ⋅6281343433.

It is a cyclic number.

It is not a de Polignac number, because 66868626521 - 2⁶ = 66868626457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66868626527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6920 + ... + 365766.

It is an arithmetic number, because the mean of its divisors is an integer number (16717292928).

Almost surely, 2^66868626521 is an apocalyptic number.

It is an amenable number.

66868626521 is a deficient number, since it is larger than the sum of its proper divisors (545191).

66868626521 is a wasteful number, since it uses less digits than its factorization.

66868626521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 545190.

The product of its digits is 9953280, while the sum is 56.

The spelling of 66868626521 in words is "sixty-six billion, eight hundred sixty-eight million, six hundred twenty-six thousand, five hundred twenty-one".