218456993 has 2 divisors, whose sum is σ = 218456994. Its totient is φ = 218456992.

The previous prime is 218456983. The next prime is 218457007. The reversal of 218456993 is 399654812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187909264 + 30547729 = 13708^2 + 5527^2 .

It is a cyclic number.

It is not a de Polignac number, because 218456993 - 2⁶ = 218456929 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (218456933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109228496 + 109228497.

It is an arithmetic number, because the mean of its divisors is an integer number (109228497).

Almost surely, 2^218456993 is an apocalyptic number.

It is an amenable number.

218456993 is a deficient number, since it is larger than the sum of its proper divisors (1).

218456993 is an equidigital number, since it uses as much as digits as its factorization.

218456993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 466560, while the sum is 47.

The square root of 218456993 is about 14780.2906940290. The cubic root of 218456993 is about 602.2664216274.

The spelling of 218456993 in words is "two hundred eighteen million, four hundred fifty-six thousand, nine hundred ninety-three".