667165621221 has 16 divisors (see below), whose sum is σ = 1078247469120. Its totient is φ = 404342800560.

The previous prime is 667165621211. The next prime is 667165621237. The reversal of 667165621221 is 122126561766.

667165621221 is a `hidden beast` number, since 6 + 6 + 7 + 16 + 5 + 621 + 2 + 2 + 1 = 666.

It is not a de Polignac number, because 667165621221 - 2¹⁴ = 667165604837 is a prime.

It is a super-2 number, since 2×667165621221² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667165621211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1123174150 + ... + 1123174743.

It is an arithmetic number, because the mean of its divisors is an integer number (67390466820).

Almost surely, 2^667165621221 is an apocalyptic number.

It is an amenable number.

667165621221 is a deficient number, since it is larger than the sum of its proper divisors (411081847899).

667165621221 is a wasteful number, since it uses less digits than its factorization.

667165621221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2246348913 (or 2246348907 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The spelling of 667165621221 in words is "six hundred sixty-seven billion, one hundred sixty-five million, six hundred twenty-one thousand, two hundred twenty-one".