1561055666 has 8 divisors (see below), whose sum is σ = 2343793644. Its totient is φ = 779791120.

The previous prime is 1561055647. The next prime is 1561055687. The reversal of 1561055666 is 6665501651.

It can be written as a sum of positive squares in 2 ways, for example, as 1546455625 + 14600041 = 39325^2 + 3821^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 365705 + ... + 369948.

Almost surely, 2^1561055666 is an apocalyptic number.

1561055666 is a deficient number, since it is larger than the sum of its proper divisors (782737978).

1561055666 is a wasteful number, since it uses less digits than its factorization.

1561055666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 736716.

The product of its (nonzero) digits is 162000, while the sum is 41.

The square root of 1561055666 is about 39510.1969876132. The cubic root of 1561055666 is about 1160.0395512674.

The spelling of 1561055666 in words is "one billion, five hundred sixty-one million, fifty-five thousand, six hundred sixty-six".