218222781 has 32 divisors (see below), whose sum is σ = 356395008. Its totient is φ = 116043840.

The previous prime is 218222777. The next prime is 218222801. The reversal of 218222781 is 187222812.

It is not a de Polignac number, because 218222781 - 2² = 218222777 is a prime.

It is a super-2 number, since 2×218222781² = 95242364294747922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218222731) 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 in 31 ways as a sum of consecutive naturals, for example, 11766 + ... + 23976.

It is an arithmetic number, because the mean of its divisors is an integer number (11137344).

Almost surely, 2^218222781 is an apocalyptic number.

218222781 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

218222781 is a deficient number, since it is larger than the sum of its proper divisors (138172227).

218222781 is a wasteful number, since it uses less digits than its factorization.

218222781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12281.

The product of its digits is 7168, while the sum is 33.

The square root of 218222781 is about 14772.3654503942. The cubic root of 218222781 is about 602.0511108064.

The spelling of 218222781 in words is "two hundred eighteen million, two hundred twenty-two thousand, seven hundred eighty-one".