66667607221 has 4 divisors (see below), whose sum is σ = 66681504000. Its totient is φ = 66653710444.

The previous prime is 66667607179. The next prime is 66667607249. The reversal of 66667607221 is 12270676666.

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 an emirpimes, since its reverse is a distinct semiprime: 12270676666 = 2 ⋅6135338333.

It is a cyclic number.

It is not a de Polignac number, because 66667607221 - 2¹⁵ = 66667574453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66667607291) 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, 6941191 + ... + 6950788.

It is an arithmetic number, because the mean of its divisors is an integer number (16670376000).

Almost surely, 2^66667607221 is an apocalyptic number.

It is an amenable number.

66667607221 is a deficient number, since it is larger than the sum of its proper divisors (13896779).

66667607221 is a wasteful number, since it uses less digits than its factorization.

66667607221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13896778.

The product of its (nonzero) digits is 1524096, while the sum is 49.

The spelling of 66667607221 in words is "sixty-six billion, six hundred sixty-seven million, six hundred seven thousand, two hundred twenty-one".