781820 has 48 divisors (see below), whose sum is σ = 1843968. Its totient is φ = 276480.

The previous prime is 781819. The next prime is 781853. The reversal of 781820 is 28187.

It is a super-2 number, since 2×781820² = 1222485024800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 781820.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 781820.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8012 + ... + 8108.

It is an arithmetic number, because the mean of its divisors is an integer number (38416).

2⁷⁸¹⁸²⁰ 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 781820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (921984).

781820 is an abundant number, since it is smaller than the sum of its proper divisors (1062148).

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

781820 is a wasteful number, since it uses less digits than its factorization.

781820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150 (or 148 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 26.

The square root of 781820 is about 884.2058583837. The cubic root of 781820 is about 92.1231809323.

The spelling of 781820 in words is "seven hundred eighty-one thousand, eight hundred twenty".