215664 has 20 divisors (see below), whose sum is σ = 557256. Its totient is φ = 71872.

The previous prime is 215659. The next prime is 215681. The reversal of 215664 is 466512.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

215664 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2199 + ... + 2294.

2²¹⁵⁶⁶⁴ is an apocalyptic number.

215664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

215664 is an abundant number, since it is smaller than the sum of its proper divisors (341592).

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

215664 is a wasteful number, since it uses less digits than its factorization.

215664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4504 (or 4498 counting only the distinct ones).

The product of its digits is 1440, while the sum is 24.

The square root of 215664 is about 464.3963824149. The cubic root of 215664 is about 59.9688727432.

The spelling of 215664 in words is "two hundred fifteen thousand, six hundred sixty-four".