1981688 has 8 divisors (see below), whose sum is σ = 3715680. Its totient is φ = 990840.

The previous prime is 1981687. The next prime is 1981691. The reversal of 1981688 is 8861891.

It is a tau number, because it is divible by the number of its divisors (8).

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981687) by changing a digit.

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 as a sum of consecutive naturals, namely, 123848 + ... + 123863.

It is an arithmetic number, because the mean of its divisors is an integer number (464460).

2^1981688 is an apocalyptic number.

It is an amenable number.

1981688 is a deficient number, since it is larger than the sum of its proper divisors (1733992).

1981688 is a wasteful number, since it uses less digits than its factorization.

1981688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247717 (or 247713 counting only the distinct ones).

The product of its digits is 27648, while the sum is 41.

The square root of 1981688 is about 1407.7244048463. The cubic root of 1981688 is about 125.6063974996.

The spelling of 1981688 in words is "one million, nine hundred eighty-one thousand, six hundred eighty-eight".