781121 has 4 divisors (see below), whose sum is σ = 852144. Its totient is φ = 710100.

The previous prime is 781117. The next prime is 781127. The reversal of 781121 is 121187.

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 781121 - 2² = 781117 is a prime.

It is a super-2 number, since 2×781121² = 1220300033282, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 781093 and 781102.

It is not an unprimeable number, because it can be changed into a prime (781127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35495 + ... + 35516.

It is an arithmetic number, because the mean of its divisors is an integer number (213036).

2⁷⁸¹¹²¹ is an apocalyptic number.

It is an amenable number.

781121 is a deficient number, since it is larger than the sum of its proper divisors (71023).

781121 is a wasteful number, since it uses less digits than its factorization.

781121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71022.

The product of its digits is 112, while the sum is 20.

The square root of 781121 is about 883.8105000508. The cubic root of 781121 is about 92.0957179596.

The spelling of 781121 in words is "seven hundred eighty-one thousand, one hundred twenty-one".