21021003823 has 2 divisors, whose sum is σ = 21021003824. Its totient is φ = 21021003822.

The previous prime is 21021003811. The next prime is 21021003827. The reversal of 21021003823 is 32830012012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021003823 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021003794 and 21021003803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021003827) 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, 10510501911 + 10510501912.

It is an arithmetic number, because the mean of its divisors is an integer number (10510501912).

Almost surely, 2^21021003823 is an apocalyptic number.

21021003823 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021003823 is an equidigital number, since it uses as much as digits as its factorization.

21021003823 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 22.

Adding to 21021003823 its reverse (32830012012), we get a palindrome (53851015835).

The spelling of 21021003823 in words is "twenty-one billion, twenty-one million, three thousand, eight hundred twenty-three".