21047782069 has 2 divisors, whose sum is σ = 21047782070. Its totient is φ = 21047782068.

The previous prime is 21047782061. The next prime is 21047782087. The reversal of 21047782069 is 96028774012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15634501444 + 5413280625 = 125038^2 + 73575^2 .

It is a cyclic number.

It is not a de Polignac number, because 21047782069 - 2³ = 21047782061 is a prime.

It is a super-2 number, since 2×21047782069² (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 (21047782061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10523891034 + 10523891035.

It is an arithmetic number, because the mean of its divisors is an integer number (10523891035).

Almost surely, 2^21047782069 is an apocalyptic number.

It is an amenable number.

21047782069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21047782069 is an equidigital number, since it uses as much as digits as its factorization.

21047782069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 338688, while the sum is 46.

The spelling of 21047782069 in words is "twenty-one billion, forty-seven million, seven hundred eighty-two thousand, sixty-nine".