221001022121261 has 2 divisors, whose sum is σ = 221001022121262. Its totient is φ = 221001022121260.

The previous prime is 221001022121203. The next prime is 221001022121263. The reversal of 221001022121261 is 162121220100122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 180955792824361 + 40045229296900 = 13451981^2 + 6328130^2 .

It is a cyclic number.

It is not a de Polignac number, because 221001022121261 - 2¹⁸ = 221001021859117 is a prime.

Together with 221001022121263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221001022121263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110500511060630 + 110500511060631.

It is an arithmetic number, because the mean of its divisors is an integer number (110500511060631).

Almost surely, 2^{221001022121261} is an apocalyptic number.

It is an amenable number.

221001022121261 is a deficient number, since it is larger than the sum of its proper divisors (1).

221001022121261 is an equidigital number, since it uses as much as digits as its factorization.

221001022121261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 384, while the sum is 23.

Adding to 221001022121261 its reverse (162121220100122), we get a palindrome (383122242221383).

The spelling of 221001022121261 in words is "two hundred twenty-one trillion, one billion, twenty-two million, one hundred twenty-one thousand, two hundred sixty-one".