11311212561 has 16 divisors (see below), whose sum is σ = 16462110720. Its totient is φ = 6851347920.

The previous prime is 11311212551. The next prime is 11311212589. The reversal of 11311212561 is 16521211311.

It is not a de Polignac number, because 11311212561 - 2⁷ = 11311212433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (11311212551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39385 + ... + 155478.

It is an arithmetic number, because the mean of its divisors is an integer number (1028881920).

Almost surely, 2^11311212561 is an apocalyptic number.

11311212561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11311212561 is a deficient number, since it is larger than the sum of its proper divisors (5150898159).

11311212561 is a wasteful number, since it uses less digits than its factorization.

11311212561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196636.

The product of its digits is 360, while the sum is 24.

Adding to 11311212561 its reverse (16521211311), we get a palindrome (27832423872).

The spelling of 11311212561 in words is "eleven billion, three hundred eleven million, two hundred twelve thousand, five hundred sixty-one".