1491391440 has 800 divisors, whose sum is σ = 6697785600. Its totient is φ = 304819200.

The previous prime is 1491391427. The next prime is 1491391457. The reversal of 1491391440 is 441931941.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1491391395 and 1491391404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 24449010 + ... + 24449070.

It is an arithmetic number, because the mean of its divisors is an integer number (8372232).

Almost surely, 2^1491391440 is an apocalyptic number.

1491391440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1491391440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3348892800).

1491391440 is an abundant number, since it is smaller than the sum of its proper divisors (5206394160).

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

1491391440 is a wasteful number, since it uses less digits than its factorization.

1491391440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 1491391440 is about 38618.5375176223. The cubic root of 1491391440 is about 1142.5201863173.

The spelling of 1491391440 in words is "one billion, four hundred ninety-one million, three hundred ninety-one thousand, four hundred forty".