218400643 has 2 divisors, whose sum is σ = 218400644. Its totient is φ = 218400642.

The previous prime is 218400631. The next prime is 218400667. The reversal of 218400643 is 346004812.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-218400643 is a prime.

It is not a weakly prime, because it can be changed into another prime (218400613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109200321 + 109200322.

It is an arithmetic number, because the mean of its divisors is an integer number (109200322).

Almost surely, 2^218400643 is an apocalyptic number.

218400643 is a deficient number, since it is larger than the sum of its proper divisors (1).

218400643 is an equidigital number, since it uses as much as digits as its factorization.

218400643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 218400643 is about 14778.3843162911. The cubic root of 218400643 is about 602.2146332016.

The spelling of 218400643 in words is "two hundred eighteen million, four hundred thousand, six hundred forty-three".