218557091 has 2 divisors, whose sum is σ = 218557092. Its totient is φ = 218557090.

The previous prime is 218557043. The next prime is 218557121. The reversal of 218557091 is 190755812.

218557091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-218557091 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (218553091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109278545 + 109278546.

It is an arithmetic number, because the mean of its divisors is an integer number (109278546).

Almost surely, 2^218557091 is an apocalyptic number.

218557091 is a deficient number, since it is larger than the sum of its proper divisors (1).

218557091 is an equidigital number, since it uses as much as digits as its factorization.

218557091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25200, while the sum is 38.

The square root of 218557091 is about 14783.6765048482. The cubic root of 218557091 is about 602.3583946637.

The spelling of 218557091 in words is "two hundred eighteen million, five hundred fifty-seven thousand, ninety-one".