217428 has 12 divisors (see below), whose sum is σ = 507360. Its totient is φ = 72472.

The previous prime is 217421. The next prime is 217429. The reversal of 217428 is 824712.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 217398 and 217407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217421) by changing a digit.

217428 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, 9048 + ... + 9071.

It is an arithmetic number, because the mean of its divisors is an integer number (42280).

2²¹⁷⁴²⁸ is an apocalyptic number.

It is an amenable number.

217428 is an abundant number, since it is smaller than the sum of its proper divisors (289932).

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

217428 is a wasteful number, since it uses less digits than its factorization.

217428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18126 (or 18124 counting only the distinct ones).

The product of its digits is 896, while the sum is 24.

The square root of 217428 is about 466.2917541626. The cubic root of 217428 is about 60.1319319091.

The spelling of 217428 in words is "two hundred seventeen thousand, four hundred twenty-eight".