1011011561 has 6 divisors (see below), whose sum is σ = 1176074730. Its totient is φ = 866581296.

The previous prime is 1011011549. The next prime is 1011011563. The reversal of 1011011561 is 1651101101.

It can be written as a sum of positive squares in only one way, i.e., 751801561 + 259210000 = 27419^2 + 16100^2 .

It is not a de Polignac number, because 1011011561 - 2²² = 1006817257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1011011563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10316396 + ... + 10316493.

It is an arithmetic number, because the mean of its divisors is an integer number (196012455).

Almost surely, 2^1011011561 is an apocalyptic number.

It is an amenable number.

1011011561 is a deficient number, since it is larger than the sum of its proper divisors (165063169).

1011011561 is an equidigital number, since it uses as much as digits as its factorization.

1011011561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20632903 (or 20632896 counting only the distinct ones).

The product of its (nonzero) digits is 30, while the sum is 17.

The square root of 1011011561 is about 31796.4079889537. The cubic root of 1011011561 is about 1003.6571294334.

Adding to 1011011561 its reverse (1651101101), we get a palindrome (2662112662).

The spelling of 1011011561 in words is "one billion, eleven million, eleven thousand, five hundred sixty-one".