1173655561 has 4 divisors (see below), whose sum is σ = 1263936772. Its totient is φ = 1083374352.

The previous prime is 1173655543. The next prime is 1173655579. The reversal of 1173655561 is 1655563711.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1173655543) and next prime (1173655579).

It can be written as a sum of positive squares in 2 ways, for example, as 768398400 + 405257161 = 27720^2 + 20131^2 .

It is a cyclic number.

It is not a de Polignac number, because 1173655561 - 2¹⁷ = 1173524489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1173655261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45140586 + ... + 45140611.

It is an arithmetic number, because the mean of its divisors is an integer number (315984193).

Almost surely, 2^1173655561 is an apocalyptic number.

It is an amenable number.

1173655561 is a deficient number, since it is larger than the sum of its proper divisors (90281211).

1173655561 is an equidigital number, since it uses as much as digits as its factorization.

1173655561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90281210.

The product of its digits is 94500, while the sum is 40.

The square root of 1173655561 is about 34258.6567308177. The cubic root of 1173655561 is about 1054.8245288155.

The spelling of 1173655561 in words is "one billion, one hundred seventy-three million, six hundred fifty-five thousand, five hundred sixty-one".