781812 has 60 divisors (see below), whose sum is σ = 2168320. Its totient is φ = 244944.

The previous prime is 781801. The next prime is 781817. The reversal of 781812 is 218187.

It is a super-2 number, since 2×781812² = 1222460006688, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781817) by changing a digit.

781812 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6093 + ... + 6219.

2⁷⁸¹⁸¹² is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 781812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1084160).

781812 is an abundant number, since it is smaller than the sum of its proper divisors (1386508).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

781812 is a wasteful number, since it uses less digits than its factorization.

781812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162 (or 151 counting only the distinct ones).

The product of its digits is 896, while the sum is 27.

The square root of 781812 is about 884.2013345387. The cubic root of 781812 is about 92.1228667134.

Adding to 781812 its reverse (218187), we get a palindrome (999999).

The spelling of 781812 in words is "seven hundred eighty-one thousand, eight hundred twelve".