217972872 has 48 divisors (see below), whose sum is σ = 635756940. Its totient is φ = 67068288.

The previous prime is 217972831. The next prime is 217972877. The reversal of 217972872 is 278279712.

It can be written as a sum of positive squares in 2 ways, for example, as 204089796 + 13883076 = 14286^2 + 3726^2 .

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (217972877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 115503 + ... + 117374.

Almost surely, 2^217972872 is an apocalyptic number.

It is an amenable number.

217972872 is an abundant number, since it is smaller than the sum of its proper divisors (417784068).

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

217972872 is a wasteful number, since it uses less digits than its factorization.

217972872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232902 (or 232895 counting only the distinct ones).

The product of its digits is 197568, while the sum is 45.

The square root of 217972872 is about 14763.9043616518. The cubic root of 217972872 is about 601.8211997925.

The spelling of 217972872 in words is "two hundred seventeen million, nine hundred seventy-two thousand, eight hundred seventy-two".