1981693 has 4 divisors (see below), whose sum is σ = 2264800. Its totient is φ = 1698588.

The previous prime is 1981691. The next prime is 1981699. The reversal of 1981693 is 3961891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1981693 - 2¹ = 1981691 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 (1981691) 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, 141543 + ... + 141556.

It is an arithmetic number, because the mean of its divisors is an integer number (566200).

2^1981693 is an apocalyptic number.

It is an amenable number.

1981693 is a deficient number, since it is larger than the sum of its proper divisors (283107).

1981693 is an equidigital number, since it uses as much as digits as its factorization.

1981693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283106.

The product of its digits is 11664, while the sum is 37.

The square root of 1981693 is about 1407.7261807610. The cubic root of 1981693 is about 125.6065031387.

It can be divided in two parts, 198 and 1693, that added together give a triangular number (1891 = T₆₁).

The spelling of 1981693 in words is "one million, nine hundred eighty-one thousand, six hundred ninety-three".