217530864 has 60 divisors (see below), whose sum is σ = 614413800. Its totient is φ = 71839872.

The previous prime is 217530857. The next prime is 217530877. The reversal of 217530864 is 468035712.

217530864 is nontrivially palindromic in base 7.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8767 + ... + 22625.

It is an arithmetic number, because the mean of its divisors is an integer number (10240230).

Almost surely, 2^217530864 is an apocalyptic number.

217530864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217530864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (307206900).

217530864 is an abundant number, since it is smaller than the sum of its proper divisors (396882936).

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

217530864 is a wasteful number, since it uses less digits than its factorization.

217530864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13982 (or 13973 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 217530864 is about 14748.9275542325. The cubic root of 217530864 is about 601.4141311036.

The spelling of 217530864 in words is "two hundred seventeen million, five hundred thirty thousand, eight hundred sixty-four".