221001212212721 has 2 divisors, whose sum is σ = 221001212212722. Its totient is φ = 221001212212720.

The previous prime is 221001212212717. The next prime is 221001212212801. The reversal of 221001212212721 is 127212212100122.

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., 220985320080625 + 15892132096 = 14865575^2 + 126064^2 .

It is a cyclic number.

It is not a de Polignac number, because 221001212212721 - 2² = 221001212212717 is a prime.

It is not a weakly prime, because it can be changed into another prime (221001212272721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110500606106360 + 110500606106361.

It is an arithmetic number, because the mean of its divisors is an integer number (110500606106361).

Almost surely, 2^{221001212212721} is an apocalyptic number.

It is an amenable number.

221001212212721 is a deficient number, since it is larger than the sum of its proper divisors (1).

221001212212721 is an equidigital number, since it uses as much as digits as its factorization.

221001212212721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 896, while the sum is 26.

Adding to 221001212212721 its reverse (127212212100122), we get a palindrome (348213424312843).

The spelling of 221001212212721 in words is "two hundred twenty-one trillion, one billion, two hundred twelve million, two hundred twelve thousand, seven hundred twenty-one".