21219747869 has 2 divisors, whose sum is σ = 21219747870. Its totient is φ = 21219747868.

The previous prime is 21219747799. The next prime is 21219747889. The reversal of 21219747869 is 96874791212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13418442244 + 7801305625 = 115838^2 + 88325^2 .

It is a cyclic number.

It is not a de Polignac number, because 21219747869 - 2³² = 16924780573 is a prime.

It is a super-2 number, since 2×21219747869² (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 (21219747889) 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, 10609873934 + 10609873935.

It is an arithmetic number, because the mean of its divisors is an integer number (10609873935).

Almost surely, 2^21219747869 is an apocalyptic number.

It is an amenable number.

21219747869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21219747869 is an equidigital number, since it uses as much as digits as its factorization.

21219747869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3048192, while the sum is 56.

The spelling of 21219747869 in words is "twenty-one billion, two hundred nineteen million, seven hundred forty-seven thousand, eight hundred sixty-nine".