1981776686 has 4 divisors (see below), whose sum is σ = 2972665032. Its totient is φ = 990888342.

The previous prime is 1981776677. The next prime is 1981776701. The reversal of 1981776686 is 6866771891.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495444170 + ... + 495444173.

It is an arithmetic number, because the mean of its divisors is an integer number (743166258).

Almost surely, 2^1981776686 is an apocalyptic number.

1981776686 is a deficient number, since it is larger than the sum of its proper divisors (990888346).

1981776686 is an equidigital number, since it uses as much as digits as its factorization.

1981776686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 990888345.

The product of its digits is 6096384, while the sum is 59.

The square root of 1981776686 is about 44517.1504703524. The cubic root of 1981776686 is about 1256.0827121582.

The spelling of 1981776686 in words is "one billion, nine hundred eighty-one million, seven hundred seventy-six thousand, six hundred eighty-six".