216811818661584 has 80 divisors (see below), whose sum is σ = 566013205197440. Its totient is φ = 71509074531840.

The previous prime is 216811818661577. The next prime is 216811818661589. The reversal of 216811818661584 is 485166818118612.

It is a super-2 number, since 2×216811818661584² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216811818661589) 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, 24696727 + ... + 32304054.

It is an arithmetic number, because the mean of its divisors is an integer number (7075165064968).

Almost surely, 2^{216811818661584} is an apocalyptic number.

216811818661584 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

216811818661584 is an abundant number, since it is smaller than the sum of its proper divisors (349201386535856).

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

216811818661584 is a wasteful number, since it uses less digits than its factorization.

216811818661584 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57001628 (or 57001622 counting only the distinct ones).

The product of its digits is 35389440, while the sum is 66.

The spelling of 216811818661584 in words is "two hundred sixteen trillion, eight hundred eleven billion, eight hundred eighteen million, six hundred sixty-one thousand, five hundred eighty-four".