216081581 has 8 divisors (see below), whose sum is σ = 227199000. Its totient is φ = 205208640.

The previous prime is 216081571. The next prime is 216081599. The reversal of 216081581 is 185180612.

It can be written as a sum of positive squares in 4 ways, for example, as 990025 + 215091556 = 995^2 + 14666^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-216081581 is a prime.

It is a super-3 number, since 3×216081581³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216081571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 59306 + ... + 62843.

It is an arithmetic number, because the mean of its divisors is an integer number (28399875).

Almost surely, 2^216081581 is an apocalyptic number.

It is an amenable number.

216081581 is a deficient number, since it is larger than the sum of its proper divisors (11117419).

216081581 is a wasteful number, since it uses less digits than its factorization.

216081581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122239.

The product of its (nonzero) digits is 3840, while the sum is 32.

The square root of 216081581 is about 14699.7136366665. The cubic root of 216081581 is about 600.0755284550.

The spelling of 216081581 in words is "two hundred sixteen million, eighty-one thousand, five hundred eighty-one".