21020400313243 has 2 divisors, whose sum is σ = 21020400313244. Its totient is φ = 21020400313242.

The previous prime is 21020400313141. The next prime is 21020400313261. The reversal of 21020400313243 is 34231300402012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21020400313243 is a prime.

It is a super-4 number, since 4×21020400313243⁴ (a number of 54 digits) contains 4444 as substring.

It is not a weakly prime, because it can be changed into another prime (21020400313543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510200156621 + 10510200156622.

It is an arithmetic number, because the mean of its divisors is an integer number (10510200156622).

Almost surely, 2^{21020400313243} is an apocalyptic number.

21020400313243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020400313243 is an equidigital number, since it uses as much as digits as its factorization.

21020400313243 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 25.

Adding to 21020400313243 its reverse (34231300402012), we get a palindrome (55251700715255).

The spelling of 21020400313243 in words is "twenty-one trillion, twenty billion, four hundred million, three hundred thirteen thousand, two hundred forty-three".