11056815561 has 24 divisors (see below), whose sum is σ = 16642458112. Its totient is φ = 6519981600.

The previous prime is 11056815557. The next prime is 11056815563. The reversal of 11056815561 is 16551865011.

It is not a de Polignac number, because 11056815561 - 2² = 11056815557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11056815563) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 398185 + ... + 425046.

Almost surely, 2^11056815561 is an apocalyptic number.

11056815561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11056815561 is a deficient number, since it is larger than the sum of its proper divisors (5585642551).

11056815561 is a wasteful number, since it uses less digits than its factorization.

11056815561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 823293 (or 823282 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 39.

The spelling of 11056815561 in words is "eleven billion, fifty-six million, eight hundred fifteen thousand, five hundred sixty-one".