217817812645812 has 18 divisors (see below), whose sum is σ = 550595026410338. Its totient is φ = 72605937548592.

The previous prime is 217817812645777. The next prime is 217817812645841. The reversal of 217817812645812 is 218546218718712.

It is a happy number.

217817812645812 is a `hidden beast` number, since 2 + 1 + 7 + 8 + 178 + 1 + 2 + 6 + 458 + 1 + 2 = 666.

217817812645812 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 175044172141476 + 42773640504336 = 13230426^2 + 6540156^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×217817812645812² (a number of 29 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 217817812645812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3025247397823 + ... + 3025247397894.

Almost surely, 2^{217817812645812} is an apocalyptic number.

It is an amenable number.

217817812645812 is an abundant number, since it is smaller than the sum of its proper divisors (332777213764526).

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

217817812645812 is a wasteful number, since it uses less digits than its factorization.

217817812645812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6050494795727 (or 6050494795722 counting only the distinct ones).

The product of its digits is 24084480, while the sum is 63.

The spelling of 217817812645812 in words is "two hundred seventeen trillion, eight hundred seventeen billion, eight hundred twelve million, six hundred forty-five thousand, eight hundred twelve".