21131212511 has 2 divisors, whose sum is σ = 21131212512. Its totient is φ = 21131212510.

The previous prime is 21131212423. The next prime is 21131212601. The reversal of 21131212511 is 11521213112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21131212511 - 2¹⁴ = 21131196127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131212811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565606255 + 10565606256.

It is an arithmetic number, because the mean of its divisors is an integer number (10565606256).

Almost surely, 2^21131212511 is an apocalyptic number.

21131212511 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131212511 is an equidigital number, since it uses as much as digits as its factorization.

21131212511 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120, while the sum is 20.

Adding to 21131212511 its reverse (11521213112), we get a palindrome (32652425623).

The spelling of 21131212511 in words is "twenty-one billion, one hundred thirty-one million, two hundred twelve thousand, five hundred eleven".