1981988 has 12 divisors (see below), whose sum is σ = 3534300. Its totient is φ = 972192.

The previous prime is 1981963. The next prime is 1981997. The reversal of 1981988 is 8891891.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1582564 + 399424 = 1258^2 + 632^2 .

It is an Ulam number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4463 + ... + 4886.

It is an arithmetic number, because the mean of its divisors is an integer number (294525).

2^1981988 is an apocalyptic number.

It is an amenable number.

1981988 is a deficient number, since it is larger than the sum of its proper divisors (1552312).

1981988 is a wasteful number, since it uses less digits than its factorization.

1981988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9406 (or 9404 counting only the distinct ones).

The product of its digits is 41472, while the sum is 44.

The square root of 1981988 is about 1407.8309557614. The cubic root of 1981988 is about 125.6127355336.

Subtracting 1981988 from its reverse (8891891), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 1981988 in words is "one million, nine hundred eighty-one thousand, nine hundred eighty-eight".