21123113131 has 2 divisors, whose sum is σ = 21123113132. Its totient is φ = 21123113130.

The previous prime is 21123113117. The next prime is 21123113149. The reversal of 21123113131 is 13131132112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21123113131 - 2¹³ = 21123104939 is a prime.

It is a super-2 number, since 2×21123113131² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21123113099 and 21123113108.

It is not a weakly prime, because it can be changed into another prime (21123113111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561556565 + 10561556566.

It is an arithmetic number, because the mean of its divisors is an integer number (10561556566).

Almost surely, 2^21123113131 is an apocalyptic number.

21123113131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123113131 is an equidigital number, since it uses as much as digits as its factorization.

21123113131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108, while the sum is 19.

Adding to 21123113131 its reverse (13131132112), we get a palindrome (34254245243).

The spelling of 21123113131 in words is "twenty-one billion, one hundred twenty-three million, one hundred thirteen thousand, one hundred thirty-one".