66121057221 has 8 divisors (see below), whose sum is σ = 88172647584. Its totient is φ = 44075085840.

The previous prime is 66121057193. The next prime is 66121057229. The reversal of 66121057221 is 12275012166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66121057221 - 2⁶ = 66121057157 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66121057229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1377210 + ... + 1424411.

It is an arithmetic number, because the mean of its divisors is an integer number (11021580948).

Almost surely, 2^66121057221 is an apocalyptic number.

It is an amenable number.

66121057221 is a deficient number, since it is larger than the sum of its proper divisors (22051590363).

66121057221 is a wasteful number, since it uses less digits than its factorization.

66121057221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2809491.

The product of its (nonzero) digits is 10080, while the sum is 33.

Adding to 66121057221 its reverse (12275012166), we get a palindrome (78396069387).

The spelling of 66121057221 in words is "sixty-six billion, one hundred twenty-one million, fifty-seven thousand, two hundred twenty-one".