66042400254221 has 4 divisors (see below), whose sum is σ = 66096845762652. Its totient is φ = 65987954745792.

The previous prime is 66042400254151. The next prime is 66042400254239. The reversal of 66042400254221 is 12245200424066.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9689903605321 + 56352496648900 = 3112861^2 + 7506830^2 .

It is a cyclic number.

It is not a de Polignac number, because 66042400254221 - 2¹⁰ = 66042400253197 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 (66042400254241) 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, 27222752396 + ... + 27222754821.

It is an arithmetic number, because the mean of its divisors is an integer number (16524211440663).

Almost surely, 2^{66042400254221} is an apocalyptic number.

It is an amenable number.

66042400254221 is a deficient number, since it is larger than the sum of its proper divisors (54445508431).

66042400254221 is a wasteful number, since it uses less digits than its factorization.

66042400254221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54445508430.

The product of its (nonzero) digits is 184320, while the sum is 38.

Adding to 66042400254221 its reverse (12245200424066), we get a palindrome (78287600678287).

The spelling of 66042400254221 in words is "sixty-six trillion, forty-two billion, four hundred million, two hundred fifty-four thousand, two hundred twenty-one".