216661543 has 4 divisors (see below), whose sum is σ = 247613200. Its totient is φ = 185709888.

The previous prime is 216661531. The next prime is 216661547. The reversal of 216661543 is 345166612.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 216661543 - 2²¹ = 214564391 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 216661499 and 216661508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216661547) 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, 15475818 + ... + 15475831.

It is an arithmetic number, because the mean of its divisors is an integer number (61903300).

Almost surely, 2^216661543 is an apocalyptic number.

216661543 is a deficient number, since it is larger than the sum of its proper divisors (30951657).

216661543 is an equidigital number, since it uses as much as digits as its factorization.

216661543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30951656.

The product of its digits is 25920, while the sum is 34.

The square root of 216661543 is about 14719.4274005479. The cubic root of 216661543 is about 600.6119155350.

The spelling of 216661543 in words is "two hundred sixteen million, six hundred sixty-one thousand, five hundred forty-three".