21123131221343 has 2 divisors, whose sum is σ = 21123131221344. Its totient is φ = 21123131221342.

The previous prime is 21123131221333. The next prime is 21123131221427. The reversal of 21123131221343 is 34312213132112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21123131221343 - 2¹⁶ = 21123131155807 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21123131221333) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561565610671 + 10561565610672.

It is an arithmetic number, because the mean of its divisors is an integer number (10561565610672).

Almost surely, 2^{21123131221343} is an apocalyptic number.

21123131221343 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123131221343 is an equidigital number, since it uses as much as digits as its factorization.

21123131221343 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 29.

Adding to 21123131221343 its reverse (34312213132112), we get a palindrome (55435344353455).

The spelling of 21123131221343 in words is "twenty-one trillion, one hundred twenty-three billion, one hundred thirty-one million, two hundred twenty-one thousand, three hundred forty-three".