1991319040 has 40 divisors (see below), whose sum is σ = 4774504680. Its totient is φ = 796526592.

The previous prime is 1991319023. The next prime is 1991319059. The reversal of 1991319040 is 409131991.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 386370 + ... + 391489.

It is an arithmetic number, because the mean of its divisors is an integer number (119362617).

Almost surely, 2^1991319040 is an apocalyptic number.

1991319040 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1991319040 is an abundant number, since it is smaller than the sum of its proper divisors (2783185640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1991319040 is an frugal number, since it uses more digits than its factorization.

1991319040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 777882 (or 777866 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 1991319040 is about 44624.1979199627. The cubic root of 1991319040 is about 1258.0955187417.

The spelling of 1991319040 in words is "one billion, nine hundred ninety-one million, three hundred nineteen thousand, forty".