218951081 has 2 divisors, whose sum is σ = 218951082. Its totient is φ = 218951080.

The previous prime is 218951077. The next prime is 218951087. The reversal of 218951081 is 180159812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 218448400 + 502681 = 14780^2 + 709^2 .

It is a cyclic number.

It is not a de Polignac number, because 218951081 - 2² = 218951077 is a prime.

It is a super-2 number, since 2×218951081² = 95879151742137122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (218951087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109475540 + 109475541.

It is an arithmetic number, because the mean of its divisors is an integer number (109475541).

Almost surely, 2^218951081 is an apocalyptic number.

It is an amenable number.

218951081 is a deficient number, since it is larger than the sum of its proper divisors (1).

218951081 is an equidigital number, since it uses as much as digits as its factorization.

218951081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 35.

The square root of 218951081 is about 14796.9956747983. The cubic root of 218951081 is about 602.7201319090.

The spelling of 218951081 in words is "two hundred eighteen million, nine hundred fifty-one thousand, eighty-one".