21112201261 has 2 divisors, whose sum is σ = 21112201262. Its totient is φ = 21112201260.

The previous prime is 21112201163. The next prime is 21112201267. The reversal of 21112201261 is 16210221112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11085984100 + 10026217161 = 105290^2 + 100131^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112201261 - 2⁷ = 21112201133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21112201267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556100630 + 10556100631.

It is an arithmetic number, because the mean of its divisors is an integer number (10556100631).

Almost surely, 2^21112201261 is an apocalyptic number.

It is an amenable number.

21112201261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112201261 is an equidigital number, since it uses as much as digits as its factorization.

21112201261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 19.

Adding to 21112201261 its reverse (16210221112), we get a palindrome (37322422373).

The spelling of 21112201261 in words is "twenty-one billion, one hundred twelve million, two hundred one thousand, two hundred sixty-one".