1321122221 has 2 divisors, whose sum is σ = 1321122222. Its totient is φ = 1321122220.

The previous prime is 1321122217. The next prime is 1321122223. The reversal of 1321122221 is 1222211231.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1020099721 + 301022500 = 31939^2 + 17350^2 .

It is a cyclic number.

It is not a de Polignac number, because 1321122221 - 2² = 1321122217 is a prime.

Together with 1321122223, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1321122221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1321122223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660561110 + 660561111.

It is an arithmetic number, because the mean of its divisors is an integer number (660561111).

Almost surely, 2^1321122221 is an apocalyptic number.

It is an amenable number.

1321122221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321122221 is an equidigital number, since it uses as much as digits as its factorization.

1321122221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96, while the sum is 17.

The square root of 1321122221 is about 36347.2450262740. The cubic root of 1321122221 is about 1097.2720893557.

Adding to 1321122221 its reverse (1222211231), we get a palindrome (2543333452).

The spelling of 1321122221 in words is "one billion, three hundred twenty-one million, one hundred twenty-two thousand, two hundred twenty-one".