213664 has 24 divisors (see below), whose sum is σ = 459648. Its totient is φ = 96960.

The previous prime is 213659. The next prime is 213713. The reversal of 213664 is 466312.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is an unprimeable number.

213664 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, 49 + ... + 655.

It is an arithmetic number, because the mean of its divisors is an integer number (19152).

2²¹³⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 213664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (229824).

213664 is an abundant number, since it is smaller than the sum of its proper divisors (245984).

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

213664 is a wasteful number, since it uses less digits than its factorization.

213664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 628 (or 620 counting only the distinct ones).

The product of its digits is 864, while the sum is 22.

The square root of 213664 is about 462.2380339176. The cubic root of 213664 is about 59.7829192500.

Adding to 213664 its reverse (466312), we get a palindrome (679976).

The spelling of 213664 in words is "two hundred thirteen thousand, six hundred sixty-four".