217506122128 has 10 divisors (see below), whose sum is σ = 421418111654. Its totient is φ = 108753061056.

The previous prime is 217506122083. The next prime is 217506122131. The reversal of 217506122128 is 821221605712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 216831785104 + 674337024 = 465652^2 + 25968^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6797066301 + ... + 6797066332.

Almost surely, 2^217506122128 is an apocalyptic number.

It is an amenable number.

217506122128 is a deficient number, since it is larger than the sum of its proper divisors (203911989526).

217506122128 is a wasteful number, since it uses less digits than its factorization.

217506122128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13594132641 (or 13594132635 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 37.

The spelling of 217506122128 in words is "two hundred seventeen billion, five hundred six million, one hundred twenty-two thousand, one hundred twenty-eight".