216556 has 6 divisors (see below), whose sum is σ = 378980. Its totient is φ = 108276.

The previous prime is 216553. The next prime is 216569. The reversal of 216556 is 655612.

It is a super-2 number, since 2×216556² = 93793002272, which contains 22 as substring.

It is an Ulam number.

It is a nialpdrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 216556.

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

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27066 + ... + 27073.

2²¹⁶⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

216556 is a deficient number, since it is larger than the sum of its proper divisors (162424).

216556 is a wasteful number, since it uses less digits than its factorization.

216556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54143 (or 54141 counting only the distinct ones).

The product of its digits is 1800, while the sum is 25.

The square root of 216556 is about 465.3557778732. The cubic root of 216556 is about 60.0514373722.

The spelling of 216556 in words is "two hundred sixteen thousand, five hundred fifty-six".