216840643 has 4 divisors (see below), whose sum is σ = 216887328. Its totient is φ = 216793960.

The previous prime is 216840641. The next prime is 216840671. The reversal of 216840643 is 346048612.

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

It is a cyclic number.

It is not a de Polignac number, because 216840643 - 2¹ = 216840641 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 216840599 and 216840608.

It is not an unprimeable number, because it can be changed into a prime (216840641) 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, 15496 + ... + 25957.

It is an arithmetic number, because the mean of its divisors is an integer number (54221832).

Almost surely, 2^216840643 is an apocalyptic number.

216840643 is a deficient number, since it is larger than the sum of its proper divisors (46685).

216840643 is an equidigital number, since it uses as much as digits as its factorization.

216840643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46684.

The product of its (nonzero) digits is 27648, while the sum is 34.

The square root of 216840643 is about 14725.5099402364. The cubic root of 216840643 is about 600.7773655512. Note that the first 3 decimals are identical.

The spelling of 216840643 in words is "two hundred sixteen million, eight hundred forty thousand, six hundred forty-three".