1581533000856 has 160 divisors (see below), whose sum is σ = 4573687324800. Its totient is φ = 510056455680.

The previous prime is 1581533000849. The next prime is 1581533000923. The reversal of 1581533000856 is 6580003351851.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 162486966 + ... + 162496698.

It is an arithmetic number, because the mean of its divisors is an integer number (28585545780).

Almost surely, 2^{1581533000856} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1581533000856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2286843662400).

1581533000856 is an abundant number, since it is smaller than the sum of its proper divisors (2992154323944).

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

1581533000856 is a wasteful number, since it uses less digits than its factorization.

1581533000856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17871 (or 17858 counting only the distinct ones).

The product of its (nonzero) digits is 432000, while the sum is 45.

The spelling of 1581533000856 in words is "one trillion, five hundred eighty-one billion, five hundred thirty-three million, eight hundred fifty-six", and thus it is an aban number.