21231549811 has 2 divisors, whose sum is σ = 21231549812. Its totient is φ = 21231549810.

The previous prime is 21231549763. The next prime is 21231549817. The reversal of 21231549811 is 11894513212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21231549811 - 2⁹ = 21231549299 is a prime.

It is the 145711-st Hogben number.

It is not a weakly prime, because it can be changed into another prime (21231549817) by changing a digit.

It is a nontrivial repunit in base 145710.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615774905 + 10615774906.

It is an arithmetic number, because the mean of its divisors is an integer number (10615774906).

Almost surely, 2^21231549811 is an apocalyptic number.

21231549811 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231549811 is an equidigital number, since it uses as much as digits as its factorization.

21231549811 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 37.

The spelling of 21231549811 in words is "twenty-one billion, two hundred thirty-one million, five hundred forty-nine thousand, eight hundred eleven".