1966856809 has 4 divisors (see below), whose sum is σ = 1974335616. Its totient is φ = 1959378004.

The previous prime is 1966856807. The next prime is 1966856819. The reversal of 1966856809 is 9086586691.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1966856809 - 2¹ = 1966856807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1966856807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3739009 + ... + 3739534.

It is an arithmetic number, because the mean of its divisors is an integer number (493583904).

Almost surely, 2^1966856809 is an apocalyptic number.

It is an amenable number.

1966856809 is a deficient number, since it is larger than the sum of its proper divisors (7478807).

1966856809 is an equidigital number, since it uses as much as digits as its factorization.

1966856809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7478806.

The product of its (nonzero) digits is 5598720, while the sum is 58.

The square root of 1966856809 is about 44349.2593962966. The cubic root of 1966856809 is about 1252.9226139233.

The spelling of 1966856809 in words is "one billion, nine hundred sixty-six million, eight hundred fifty-six thousand, eight hundred nine".