1981045 has 16 divisors (see below), whose sum is σ = 2620800. Its totient is φ = 1425600.

The previous prime is 1981037. The next prime is 1981081. The reversal of 1981045 is 5401891.

It is a happy number.

1981045 is a nontrivial binomial coefficient, being equal to C(1991, 2).

It is not a de Polignac number, because 1981045 - 2³ = 1981037 is a prime.

It is a congruent number.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 9856 + ... + 10054.

It is an arithmetic number, because the mean of its divisors is an integer number (163800).

2^1981045 is an apocalyptic number.

1981045 is the 1990-th triangular number.

1981045 is the 664-th centered nonagonal number.

It is an amenable number.

1981045 is a deficient number, since it is larger than the sum of its proper divisors (639755).

1981045 is a wasteful number, since it uses less digits than its factorization.

1981045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 1981045 is about 1407.4960035467. The cubic root of 1981045 is about 125.5928108249.

The spelling of 1981045 in words is "one million, nine hundred eighty-one thousand, forty-five".