216551566 has 32 divisors (see below), whose sum is σ = 405907200. Its totient is φ = 84177600.

The previous prime is 216551563. The next prime is 216551567. The reversal of 216551566 is 665155612.

216551566 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216551563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78885 + ... + 81583.

It is an arithmetic number, because the mean of its divisors is an integer number (12684600).

Almost surely, 2^216551566 is an apocalyptic number.

216551566 is a deficient number, since it is larger than the sum of its proper divisors (189355634).

216551566 is a wasteful number, since it uses less digits than its factorization.

216551566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3240.

The product of its digits is 54000, while the sum is 37.

The square root of 216551566 is about 14715.6911492461. The cubic root of 216551566 is about 600.5102751683.

It can be divided in two parts, 21655 and 1566, that multiplied together give a triangular number (33911730 = T₈₂₃₅).

The spelling of 216551566 in words is "two hundred sixteen million, five hundred fifty-one thousand, five hundred sixty-six".