217620858817 has 4 divisors (see below), whose sum is σ = 217817091540. Its totient is φ = 217424626096.

The previous prime is 217620858811. The next prime is 217620858823. The reversal of 217620858817 is 718858026712.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (217620858811) and next prime (217620858823).

It can be written as a sum of positive squares in 2 ways, for example, as 23147796736 + 194473062081 = 152144^2 + 440991^2 .

It is a cyclic number.

It is not a de Polignac number, because 217620858817 - 2²⁷ = 217486641089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217620858811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 98114698 + ... + 98116915.

It is an arithmetic number, because the mean of its divisors is an integer number (54454272885).

Almost surely, 2^217620858817 is an apocalyptic number.

It is an amenable number.

217620858817 is a deficient number, since it is larger than the sum of its proper divisors (196232723).

217620858817 is a wasteful number, since it uses less digits than its factorization.

217620858817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196232722.

The product of its (nonzero) digits is 3010560, while the sum is 55.

It can be divided in two parts, 2176208 and 58817, that added together give a square (2235025 = 1495²).

The spelling of 217620858817 in words is "two hundred seventeen billion, six hundred twenty million, eight hundred fifty-eight thousand, eight hundred seventeen".