217987872 has 48 divisors (see below), whose sum is σ = 605882592. Its totient is φ = 68387840.

The previous prime is 217987871. The next prime is 217987921. The reversal of 217987872 is 278789712.

It is a happy number.

217987872 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (51).

It is not an unprimeable number, because it can be changed into a prime (217987871) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65154 + ... + 68417.

It is an arithmetic number, because the mean of its divisors is an integer number (12622554).

Almost surely, 2^217987872 is an apocalyptic number.

It is an amenable number.

217987872 is an abundant number, since it is smaller than the sum of its proper divisors (387894720).

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

217987872 is a wasteful number, since it uses less digits than its factorization.

217987872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133601 (or 133593 counting only the distinct ones).

The product of its digits is 790272, while the sum is 51.

The square root of 217987872 is about 14764.4123486172. The cubic root of 217987872 is about 601.8350044322.

The spelling of 217987872 in words is "two hundred seventeen million, nine hundred eighty-seven thousand, eight hundred seventy-two".