1556066791 has 4 divisors (see below), whose sum is σ = 1556150472. Its totient is φ = 1555983112.

The previous prime is 1556066789. The next prime is 1556066849. The reversal of 1556066791 is 1976606551.

1556066791 is a nontrivial binomial coefficient, being equal to C(55787, 2).

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1976606551 = 331 ⋅5971621.

It is not a de Polignac number, because 1556066791 - 2¹ = 1556066789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1556067791) 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, 1 + ... + 55786.

It is an arithmetic number, because the mean of its divisors is an integer number (389037618).

Almost surely, 2^1556066791 is an apocalyptic number.

1556066791 is the 55786-th triangular number.

1556066791 is the 18596-th centered nonagonal number.

1556066791 is a deficient number, since it is larger than the sum of its proper divisors (83681).

1556066791 is an equidigital number, since it uses as much as digits as its factorization.

1556066791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83680.

The product of its (nonzero) digits is 340200, while the sum is 46.

The square root of 1556066791 is about 39447.0124470789. The cubic root of 1556066791 is about 1158.8024678229.

The spelling of 1556066791 in words is "one billion, five hundred fifty-six million, sixty-six thousand, seven hundred ninety-one".