815131981440 has 1536 divisors, whose sum is σ = 3488546880000. Its totient is φ = 174997831680.

The previous prime is 815131981397. The next prime is 815131981453. The reversal of 815131981440 is 44189131518.

815131981440 is a `hidden beast` number, since 8 + 1 + 5 + 13 + 198 + 1 + 440 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 2349083347 + ... + 2349083693.

It is an arithmetic number, because the mean of its divisors is an integer number (2271189375).

Almost surely, 2^815131981440 is an apocalyptic number.

815131981440 is a gapful number since it is divisible by the number (80) 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 815131981440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1744273440000).

815131981440 is an abundant number, since it is smaller than the sum of its proper divisors (2673414898560).

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

815131981440 is a wasteful number, since it uses less digits than its factorization.

815131981440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 463 (or 434 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The spelling of 815131981440 in words is "eight hundred fifteen billion, one hundred thirty-one million, nine hundred eighty-one thousand, four hundred forty".