1981909568 has 14 divisors (see below), whose sum is σ = 3932851926. Its totient is φ = 990954752.

The previous prime is 1981909547. The next prime is 1981909571. The reversal of 1981909568 is 8659091891.

It can be written as a sum of positive squares in only one way, i.e., 1716610624 + 265298944 = 41432^2 + 16288^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15483605 + ... + 15483732.

Almost surely, 2^1981909568 is an apocalyptic number.

It is an amenable number.

1981909568 is a deficient number, since it is larger than the sum of its proper divisors (1950942358).

1981909568 is an equidigital number, since it uses as much as digits as its factorization.

1981909568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30967349 (or 30967339 counting only the distinct ones).

The product of its (nonzero) digits is 1399680, while the sum is 56.

The square root of 1981909568 is about 44518.6429263067. The cubic root of 1981909568 is about 1256.1107857976.

The spelling of 1981909568 in words is "one billion, nine hundred eighty-one million, nine hundred nine thousand, five hundred sixty-eight".