1981566504 has 80 divisors (see below), whose sum is σ = 5557000020. Its totient is φ = 659715840.

The previous prime is 1981566467. The next prime is 1981566523. The reversal of 1981566504 is 4056651891.

1981566504 is a `hidden beast` number, since 1 + 9 + 81 + 5 + 66 + 504 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1218149604 + 763416900 = 34902^2 + 27630^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1981566504.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 784764 + ... + 787284.

Almost surely, 2^1981566504 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 1981566504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2778500010).

1981566504 is an abundant number, since it is smaller than the sum of its proper divisors (3575433516).

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

1981566504 is a wasteful number, since it uses less digits than its factorization.

1981566504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3752 (or 3739 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 45.

The square root of 1981566504 is about 44514.7897220688. The cubic root of 1981566504 is about 1256.0383049835.

The spelling of 1981566504 in words is "one billion, nine hundred eighty-one million, five hundred sixty-six thousand, five hundred four".