1981783 has 4 divisors (see below), whose sum is σ = 1984680. Its totient is φ = 1978888.

The previous prime is 1981753. The next prime is 1981787. The reversal of 1981783 is 3871891.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 3871891 = 1693 ⋅2287.

It is a cyclic number.

It is not a de Polignac number, because 1981783 - 2¹³ = 1973591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 216 + ... + 2002.

It is an arithmetic number, because the mean of its divisors is an integer number (496170).

2^1981783 is an apocalyptic number.

1981783 is a deficient number, since it is larger than the sum of its proper divisors (2897).

1981783 is a wasteful number, since it uses less digits than its factorization.

1981783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2896.

The product of its digits is 12096, while the sum is 37.

The square root of 1981783 is about 1407.7581468420. The cubic root of 1981783 is about 125.6084046129.

It can be divided in two parts, 19817 and 83, that added together give a triangular number (19900 = T₁₉₉).

The spelling of 1981783 in words is "one million, nine hundred eighty-one thousand, seven hundred eighty-three".