20021712172218 has 24 divisors (see below), whose sum is σ = 43381053526356. Its totient is φ = 6673799880000.

The previous prime is 20021712172211. The next prime is 20021712172223. The reversal of 20021712172218 is 81227121712002.

20021712172218 is a `hidden beast` number, since 2 + 0 + 0 + 217 + 1 + 217 + 221 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 19598922222489 + 422789949729 = 4427067^2 + 650223^2 .

It is not an unprimeable number, because it can be changed into a prime (20021712172211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7491883 + ... + 9806718.

Almost surely, 2^{20021712172218} is an apocalyptic number.

20021712172218 is an abundant number, since it is smaller than the sum of its proper divisors (23359341354138).

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

20021712172218 is a wasteful number, since it uses less digits than its factorization.

20021712172218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17362910 (or 17362907 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The spelling of 20021712172218 in words is "twenty trillion, twenty-one billion, seven hundred twelve million, one hundred seventy-two thousand, two hundred eighteen".