1981666944 has 128 divisors (see below), whose sum is σ = 5921712000. Its totient is φ = 660462336.

The previous prime is 1981666943. The next prime is 1981666961. The reversal of 1981666944 is 4496661891.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1981666943) 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, 276397 + ... + 283475.

It is an arithmetic number, because the mean of its divisors is an integer number (46263375).

Almost surely, 2^1981666944 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 1981666944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2960856000).

1981666944 is an abundant number, since it is smaller than the sum of its proper divisors (3940045056).

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

1981666944 is an frugal number, since it uses more digits than its factorization.

1981666944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7114 (or 7084 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 54.

The square root of 1981666944 is about 44515.9178721500. The cubic root of 1981666944 is about 1256.0595263010.

The spelling of 1981666944 in words is "one billion, nine hundred eighty-one million, six hundred sixty-six thousand, nine hundred forty-four".