216557 has 4 divisors (see below), whose sum is σ = 236256. Its totient is φ = 196860.

The previous prime is 216553. The next prime is 216569. The reversal of 216557 is 755612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 216557 - 2² = 216553 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9833 + ... + 9854.

It is an arithmetic number, because the mean of its divisors is an integer number (59064).

2²¹⁶⁵⁵⁷ is an apocalyptic number.

It is an amenable number.

216557 is a deficient number, since it is larger than the sum of its proper divisors (19699).

216557 is a wasteful number, since it uses less digits than its factorization.

216557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19698.

The product of its digits is 2100, while the sum is 26.

The square root of 216557 is about 465.3568523187. The cubic root of 216557 is about 60.0515298061.

It can be divided in two parts, 2165 and 57, that added together give a palindrome (2222).

The spelling of 216557 in words is "two hundred sixteen thousand, five hundred fifty-seven".