217106720656 has 80 divisors (see below), whose sum is σ = 516184462080. Its totient is φ = 86338990080.

The previous prime is 217106720627. The next prime is 217106720729. The reversal of 217106720656 is 656027601712.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 667821 + ... + 938188.

It is an arithmetic number, because the mean of its divisors is an integer number (6452305776).

Almost surely, 2^217106720656 is an apocalyptic number.

It is an amenable number.

217106720656 is an abundant number, since it is smaller than the sum of its proper divisors (299077741424).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217106720656 is a wasteful number, since it uses less digits than its factorization.

217106720656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1606112 (or 1606106 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 43.

The spelling of 217106720656 in words is "two hundred seventeen billion, one hundred six million, seven hundred twenty thousand, six hundred fifty-six".