21220219261 has 2 divisors, whose sum is σ = 21220219262. Its totient is φ = 21220219260.

The previous prime is 21220219219. The next prime is 21220219289. The reversal of 21220219261 is 16291202212.

It is an a-pointer prime, because the next prime (21220219289) can be obtained adding 21220219261 to its sum of digits (28).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19001244025 + 2218975236 = 137845^2 + 47106^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220219261 - 2²⁷ = 21086001533 is a prime.

It is a super-2 number, since 2×21220219261² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220219211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610109630 + 10610109631.

It is an arithmetic number, because the mean of its divisors is an integer number (10610109631).

Almost surely, 2^21220219261 is an apocalyptic number.

It is an amenable number.

21220219261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220219261 is an equidigital number, since it uses as much as digits as its factorization.

21220219261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 28.

The spelling of 21220219261 in words is "twenty-one billion, two hundred twenty million, two hundred nineteen thousand, two hundred sixty-one".