221212321121261 has 2 divisors, whose sum is σ = 221212321121262. Its totient is φ = 221212321121260.

The previous prime is 221212321121191. The next prime is 221212321121269. The reversal of 221212321121261 is 162121123212122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 218082570929161 + 3129750192100 = 14767619^2 + 1769110^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221212321121261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221212321121269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110606160560630 + 110606160560631.

It is an arithmetic number, because the mean of its divisors is an integer number (110606160560631).

Almost surely, 2^{221212321121261} is an apocalyptic number.

It is an amenable number.

221212321121261 is a deficient number, since it is larger than the sum of its proper divisors (1).

221212321121261 is an equidigital number, since it uses as much as digits as its factorization.

221212321121261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 29.

Adding to 221212321121261 its reverse (162121123212122), we get a palindrome (383333444333383).

The spelling of 221212321121261 in words is "two hundred twenty-one trillion, two hundred twelve billion, three hundred twenty-one million, one hundred twenty-one thousand, two hundred sixty-one".