21811420769 has 2 divisors, whose sum is σ = 21811420770. Its totient is φ = 21811420768.

The previous prime is 21811420721. The next prime is 21811420777. The reversal of 21811420769 is 96702411812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15508966225 + 6302454544 = 124535^2 + 79388^2 .

It is a cyclic number.

It is not a de Polignac number, because 21811420769 - 2²⁰ = 21810372193 is a prime.

It is a super-2 number, since 2×21811420769² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21811429769) 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, 10905710384 + 10905710385.

It is an arithmetic number, because the mean of its divisors is an integer number (10905710385).

Almost surely, 2^21811420769 is an apocalyptic number.

It is an amenable number.

21811420769 is a deficient number, since it is larger than the sum of its proper divisors (1).

21811420769 is an equidigital number, since it uses as much as digits as its factorization.

21811420769 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48384, while the sum is 41.

The spelling of 21811420769 in words is "twenty-one billion, eight hundred eleven million, four hundred twenty thousand, seven hundred sixty-nine".