221206651 has 2 divisors, whose sum is σ = 221206652. Its totient is φ = 221206650.

The previous prime is 221206649. The next prime is 221206673. The reversal of 221206651 is 156602122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221206651 - 2¹ = 221206649 is a prime.

Together with 221206649, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (221206621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110603325 + 110603326.

It is an arithmetic number, because the mean of its divisors is an integer number (110603326).

Almost surely, 2^221206651 is an apocalyptic number.

221206651 is a deficient number, since it is larger than the sum of its proper divisors (1).

221206651 is an equidigital number, since it uses as much as digits as its factorization.

221206651 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 221206651 is about 14873.0175485676. The cubic root of 221206651 is about 604.7827473940.

Adding to 221206651 its reverse (156602122), we get a palindrome (377808773).

The spelling of 221206651 in words is "two hundred twenty-one million, two hundred six thousand, six hundred fifty-one".