781993 has 4 divisors (see below), whose sum is σ = 801108. Its totient is φ = 762880.

The previous prime is 781987. The next prime is 781997. The reversal of 781993 is 399187.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 21609 + 760384 = 147^2 + 872^2 .

It is a cyclic number.

It is not a de Polignac number, because 781993 - 2⁵ = 781961 is a prime.

It is a super-2 number, since 2×781993² = 1223026104098, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (781997) 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, 9496 + ... + 9577.

It is an arithmetic number, because the mean of its divisors is an integer number (200277).

2⁷⁸¹⁹⁹³ is an apocalyptic number.

It is an amenable number.

781993 is a deficient number, since it is larger than the sum of its proper divisors (19115).

781993 is a wasteful number, since it uses less digits than its factorization.

781993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19114.

The product of its digits is 13608, while the sum is 37.

The square root of 781993 is about 884.3036808699. The cubic root of 781993 is about 92.1299753926.

The spelling of 781993 in words is "seven hundred eighty-one thousand, nine hundred ninety-three".