218211947 has 2 divisors, whose sum is σ = 218211948. Its totient is φ = 218211946.

The previous prime is 218211943. The next prime is 218211997. The reversal of 218211947 is 749112812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 218211947 - 2² = 218211943 is a prime.

It is not a weakly prime, because it can be changed into another prime (218211943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109105973 + 109105974.

It is an arithmetic number, because the mean of its divisors is an integer number (109105974).

Almost surely, 2^218211947 is an apocalyptic number.

218211947 is a deficient number, since it is larger than the sum of its proper divisors (1).

218211947 is an equidigital number, since it uses as much as digits as its factorization.

218211947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 35.

The square root of 218211947 is about 14771.9987476306. The cubic root of 218211947 is about 602.0411473955.

The spelling of 218211947 in words is "two hundred eighteen million, two hundred eleven thousand, nine hundred forty-seven".