1981506856 has 64 divisors (see below), whose sum is σ = 4573716480. Its totient is φ = 786075840.

The previous prime is 1981506847. The next prime is 1981506889. The reversal of 1981506856 is 6586051891.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15115 + ... + 64741.

It is an arithmetic number, because the mean of its divisors is an integer number (71464320).

Almost surely, 2^1981506856 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 1981506856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2286858240).

1981506856 is an abundant number, since it is smaller than the sum of its proper divisors (2592209624).

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

1981506856 is a wasteful number, since it uses less digits than its factorization.

1981506856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49694 (or 49690 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 49.

The square root of 1981506856 is about 44514.1197374496. The cubic root of 1981506856 is about 1256.0257020042.

The spelling of 1981506856 in words is "one billion, nine hundred eighty-one million, five hundred six thousand, eight hundred fifty-six".