221966681 has 2 divisors, whose sum is σ = 221966682. Its totient is φ = 221966680.

The previous prime is 221966669. The next prime is 221966713. The reversal of 221966681 is 186669122.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199261456 + 22705225 = 14116^2 + 4765^2 .

It is a cyclic number.

It is not a de Polignac number, because 221966681 - 2²² = 217772377 is a prime.

It is a super-2 number, since 2×221966681² = 98538414948311522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221966611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110983340 + 110983341.

It is an arithmetic number, because the mean of its divisors is an integer number (110983341).

Almost surely, 2^221966681 is an apocalyptic number.

It is an amenable number.

221966681 is a deficient number, since it is larger than the sum of its proper divisors (1).

221966681 is an equidigital number, since it uses as much as digits as its factorization.

221966681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 41.

The square root of 221966681 is about 14898.5462713649. The cubic root of 221966681 is about 605.4746006166.

The spelling of 221966681 in words is "two hundred twenty-one million, nine hundred sixty-six thousand, six hundred eighty-one".