1172681561 has 4 divisors (see below), whose sum is σ = 1174478052. Its totient is φ = 1170885072.

The previous prime is 1172681557. The next prime is 1172681567. The reversal of 1172681561 is 1651862711.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1651862711 = 127 ⋅13006793.

It can be written as a sum of positive squares in 2 ways, for example, as 826907536 + 345774025 = 28756^2 + 18595^2 .

It is a cyclic number.

It is not a de Polignac number, because 1172681561 - 2² = 1172681557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1172681567) 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 3 ways as a sum of consecutive naturals, for example, 897266 + ... + 898571.

It is an arithmetic number, because the mean of its divisors is an integer number (293619513).

Almost surely, 2^1172681561 is an apocalyptic number.

It is an amenable number.

1172681561 is a deficient number, since it is larger than the sum of its proper divisors (1796491).

1172681561 is an equidigital number, since it uses as much as digits as its factorization.

1172681561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1796490.

The product of its digits is 20160, while the sum is 38.

The square root of 1172681561 is about 34244.4383951613. The cubic root of 1172681561 is about 1054.5326534521.

The spelling of 1172681561 in words is "one billion, one hundred seventy-two million, six hundred eighty-one thousand, five hundred sixty-one".