221202122221 has 6 divisors (see below), whose sum is σ = 233457087822. Its totient is φ = 209559904920.

The previous prime is 221202122213. The next prime is 221202122237. The reversal of 221202122221 is 122221202122.

It can be written as a sum of positive squares in only one way, i.e., 221135062500 + 67059721 = 470250^2 + 8189^2 .

It is not a de Polignac number, because 221202122221 - 2³ = 221202122213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221202122201) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 306373770 + ... + 306374491.

It is an arithmetic number, because the mean of its divisors is an integer number (38909514637).

Almost surely, 2^221202122221 is an apocalyptic number.

It is an amenable number.

221202122221 is a deficient number, since it is larger than the sum of its proper divisors (12254965601).

221202122221 is an equidigital number, since it uses as much as digits as its factorization.

221202122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 612748299 (or 612748280 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 221202122221 its reverse (122221202122), we get a palindrome (343423324343).

The spelling of 221202122221 in words is "two hundred twenty-one billion, two hundred two million, one hundred twenty-two thousand, two hundred twenty-one".