8561867661 has 12 divisors (see below), whose sum is σ = 12372556092. Its totient is φ = 5705413056.

The previous prime is 8561867653. The next prime is 8561867701. The reversal of 8561867661 is 1667681658.

8561867661 is a `hidden beast` number, since 8 + 561 + 8 + 6 + 76 + 6 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 3502390761 + 5059476900 = 59181^2 + 71130^2 .

It is not a de Polignac number, because 8561867661 - 2³ = 8561867653 is a prime.

It is a super-2 number, since 2×8561867661² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 8561867598 and 8561867607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8561867621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 186406 + ... + 227751.

It is an arithmetic number, because the mean of its divisors is an integer number (1031046341).

Almost surely, 2^8561867661 is an apocalyptic number.

It is an amenable number.

8561867661 is a deficient number, since it is larger than the sum of its proper divisors (3810688431).

8561867661 is a wasteful number, since it uses less digits than its factorization.

8561867661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 416460 (or 416457 counting only the distinct ones).

The product of its digits is 2903040, while the sum is 54.

The square root of 8561867661 is about 92530.3607525660. The cubic root of 8561867661 is about 2045.7670069189.

The spelling of 8561867661 in words is "eight billion, five hundred sixty-one million, eight hundred sixty-seven thousand, six hundred sixty-one".