1581156440 has 64 divisors (see below), whose sum is σ = 3832012800. Its totient is φ = 585228672.

The previous prime is 1581156427. The next prime is 1581156449. The reversal of 1581156440 is 446511851.

It is a self number, because there is not a number n which added to its sum of digits gives 1581156440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581156449) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8489 + ... + 56871.

It is an arithmetic number, because the mean of its divisors is an integer number (59875200).

Almost surely, 2^1581156440 is an apocalyptic number.

1581156440 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 1581156440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1916006400).

1581156440 is an abundant number, since it is smaller than the sum of its proper divisors (2250856360).

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

1581156440 is a wasteful number, since it uses less digits than its factorization.

1581156440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48456 (or 48452 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 1581156440 is about 39763.7578707043. The cubic root of 1581156440 is about 1164.9973757670.

The spelling of 1581156440 in words is "one billion, five hundred eighty-one million, one hundred fifty-six thousand, four hundred forty".