21759477869 has 2 divisors, whose sum is σ = 21759477870. Its totient is φ = 21759477868.

The previous prime is 21759477851. The next prime is 21759477877. The reversal of 21759477869 is 96877495712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21737668969 + 21808900 = 147437^2 + 4670^2 .

It is a cyclic number.

It is not a de Polignac number, because 21759477869 - 2⁸ = 21759477613 is a prime.

It is a super-2 number, since 2×21759477869² (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 (21759477769) 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, 10879738934 + 10879738935.

It is an arithmetic number, because the mean of its divisors is an integer number (10879738935).

Almost surely, 2^21759477869 is an apocalyptic number.

It is an amenable number.

21759477869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21759477869 is an equidigital number, since it uses as much as digits as its factorization.

21759477869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 53343360, while the sum is 65.

The spelling of 21759477869 in words is "twenty-one billion, seven hundred fifty-nine million, four hundred seventy-seven thousand, eight hundred sixty-nine".