1186161561 has 24 divisors (see below), whose sum is σ = 1846845000. Its totient is φ = 729271296.

The previous prime is 1186161527. The next prime is 1186161563. The reversal of 1186161561 is 1651616811.

1186161561 is a `hidden beast` number, since 1 + 1 + 86 + 16 + 1 + 561 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 170145936 + 1016015625 = 13044^2 + 31875^2 .

It is not a de Polignac number, because 1186161561 - 2¹⁸ = 1185899417 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1186161563) 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, 142075 + ... + 150191.

It is an arithmetic number, because the mean of its divisors is an integer number (76951875).

Almost surely, 2^1186161561 is an apocalyptic number.

It is an amenable number.

1186161561 is a deficient number, since it is larger than the sum of its proper divisors (660683439).

1186161561 is a wasteful number, since it uses less digits than its factorization.

1186161561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9385 (or 9382 counting only the distinct ones).

The product of its digits is 8640, while the sum is 36.

The square root of 1186161561 is about 34440.6962908708. The cubic root of 1186161561 is about 1058.5578944623.

The spelling of 1186161561 in words is "one billion, one hundred eighty-six million, one hundred sixty-one thousand, five hundred sixty-one".