1581000000 has 392 divisors, whose sum is σ = 5714926848. Its totient is φ = 384000000.

The previous prime is 1580999999. The next prime is 1581000011. The reversal of 1581000000 is 1851.

It is a happy number.

It is a super-2 number, since 2×1581000000² = 4999122000000000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

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 55 ways as a sum of consecutive naturals, for example, 50999985 + ... + 51000015.

Almost surely, 2^1581000000 is an apocalyptic number.

1581000000 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 1581000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2857463424).

1581000000 is an abundant number, since it is smaller than the sum of its proper divisors (4133926848).

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

1581000000 is an frugal number, since it uses more digits than its factorization.

1581000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 15.

The square root of 1581000000 is about 39761.7907041421. The cubic root of 1581000000 is about 1164.9589527925.

Adding to 1581000000 its reverse (1851), we get a palindrome (1581001851).

The spelling of 1581000000 in words is "one billion, five hundred eighty-one million", and thus it is an aban number.