1801993 has 4 divisors (see below), whose sum is σ = 1812240. Its totient is φ = 1791748.

The previous prime is 1801967. The next prime is 1801997. The reversal of 1801993 is 3991081.

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, and also an emirpimes, since its reverse is a distinct semiprime: 3991081 = 151 ⋅26431.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1801993 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1801997) 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 in 3 ways as a sum of consecutive naturals, for example, 4855 + ... + 5212.

It is an arithmetic number, because the mean of its divisors is an integer number (453060).

2^1801993 is an apocalyptic number.

It is an amenable number.

1801993 is a deficient number, since it is larger than the sum of its proper divisors (10247).

1801993 is a wasteful number, since it uses less digits than its factorization.

1801993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10246.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 1801993 is about 1342.3833282636. The cubic root of 1801993 is about 121.6889190132.

The spelling of 1801993 in words is "one million, eight hundred one thousand, nine hundred ninety-three".