216643641 has 4 divisors (see below), whose sum is σ = 288858192. Its totient is φ = 144429092.

The previous prime is 216643627. The next prime is 216643657. The reversal of 216643641 is 146346612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 216643641 - 2⁶ = 216643577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216643741) 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, 36107271 + ... + 36107276.

It is an arithmetic number, because the mean of its divisors is an integer number (72214548).

Almost surely, 2^216643641 is an apocalyptic number.

It is an amenable number.

216643641 is a deficient number, since it is larger than the sum of its proper divisors (72214551).

216643641 is an equidigital number, since it uses as much as digits as its factorization.

216643641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72214550.

The product of its digits is 20736, while the sum is 33.

The square root of 216643641 is about 14718.8192800917. The cubic root of 216643641 is about 600.5953729120.

The spelling of 216643641 in words is "two hundred sixteen million, six hundred forty-three thousand, six hundred forty-one".