21761130221 has 2 divisors, whose sum is σ = 21761130222. Its totient is φ = 21761130220.

The previous prime is 21761130151. The next prime is 21761130247. The reversal of 21761130221 is 12203116712.

It is an a-pointer prime, because the next prime (21761130247) can be obtained adding 21761130221 to its sum of digits (26).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11650827721 + 10110302500 = 107939^2 + 100550^2 .

It is a cyclic number.

It is not a de Polignac number, because 21761130221 - 2¹⁴ = 21761113837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21761138221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10880565110 + 10880565111.

It is an arithmetic number, because the mean of its divisors is an integer number (10880565111).

Almost surely, 2^21761130221 is an apocalyptic number.

It is an amenable number.

21761130221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21761130221 is an equidigital number, since it uses as much as digits as its factorization.

21761130221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 26.

Adding to 21761130221 its reverse (12203116712), we get a palindrome (33964246933).

The spelling of 21761130221 in words is "twenty-one billion, seven hundred sixty-one million, one hundred thirty thousand, two hundred twenty-one".