1438931991 has 64 divisors (see below), whose sum is σ = 2342912000. Its totient is φ = 784274400.

The previous prime is 1438931987. The next prime is 1438931993. The reversal of 1438931991 is 1991398341.

It is not a de Polignac number, because 1438931991 - 2² = 1438931987 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1438931991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1438931993) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2519736 + ... + 2520306.

It is an arithmetic number, because the mean of its divisors is an integer number (36608000).

Almost surely, 2^1438931991 is an apocalyptic number.

1438931991 is a deficient number, since it is larger than the sum of its proper divisors (903980009).

1438931991 is an equidigital number, since it uses as much as digits as its factorization.

1438931991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 705 (or 691 counting only the distinct ones).

The product of its digits is 209952, while the sum is 48.

The square root of 1438931991 is about 37933.2570576269. The cubic root of 1438931991 is about 1128.9639892351.

The spelling of 1438931991 in words is "one billion, four hundred thirty-eight million, nine hundred thirty-one thousand, nine hundred ninety-one".