21047287813 has 2 divisors, whose sum is σ = 21047287814. Its totient is φ = 21047287812.

The previous prime is 21047287763. The next prime is 21047287831. The reversal of 21047287813 is 31878274012.

Together with next prime (21047287831) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20291147809 + 756140004 = 142447^2 + 27498^2 .

It is a cyclic number.

It is not a de Polignac number, because 21047287813 - 2²⁵ = 21013733381 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21047287813.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21047287883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10523643906 + 10523643907.

It is an arithmetic number, because the mean of its divisors is an integer number (10523643907).

Almost surely, 2^21047287813 is an apocalyptic number.

It is an amenable number.

21047287813 is a deficient number, since it is larger than the sum of its proper divisors (1).

21047287813 is an equidigital number, since it uses as much as digits as its factorization.

21047287813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 150528, while the sum is 43.

The spelling of 21047287813 in words is "twenty-one billion, forty-seven million, two hundred eighty-seven thousand, eight hundred thirteen".