21185065723 has 2 divisors, whose sum is σ = 21185065724. Its totient is φ = 21185065722.

The previous prime is 21185065673. The next prime is 21185065739. The reversal of 21185065723 is 32756058112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21185065723 - 2²¹ = 21182968571 is a prime.

It is not a weakly prime, because it can be changed into another prime (21185065793) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10592532861 + 10592532862.

It is an arithmetic number, because the mean of its divisors is an integer number (10592532862).

Almost surely, 2^21185065723 is an apocalyptic number.

21185065723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21185065723 is an equidigital number, since it uses as much as digits as its factorization.

21185065723 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 100800, while the sum is 40.

The spelling of 21185065723 in words is "twenty-one billion, one hundred eighty-five million, sixty-five thousand, seven hundred twenty-three".