1101561499809 has 45 divisors (see below), whose sum is σ = 1655436651561. Its totient is φ = 729985102560.

The previous prime is 1101561499789. The next prime is 1101561499853. The reversal of 1101561499809 is 9089941651011.

The square root of 1101561499809 is 1049553.

It is a perfect power (a square), and thus also a powerful number.

1101561499809 is a `hidden beast` number, since 1 + 1 + 0 + 15 + 61 + 499 + 80 + 9 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 851089277025 + 250472222784 = 922545^2 + 500472^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1101561499809 is a prime.

It is a super-3 number, since 3×1101561499809³ (a number of 37 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (1101561499889) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 2616535419 + ... + 2616535839.

Almost surely, 2^{1101561499809} is an apocalyptic number.

1101561499809 is the 1049553-rd square number.

1101561499809 is the 524777-th centered octagonal number.

It is an amenable number.

1101561499809 is a deficient number, since it is larger than the sum of its proper divisors (553875151752).

1101561499809 is an frugal number, since it uses more digits than its factorization.

1101561499809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408 (or 701 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 54.

The spelling of 1101561499809 in words is "one trillion, one hundred one billion, five hundred sixty-one million, four hundred ninety-nine thousand, eight hundred nine".