781020 has 36 divisors (see below), whose sum is σ = 2369640. Its totient is φ = 208224.

The previous prime is 781007. The next prime is 781021. The reversal of 781020 is 20187.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 780984 and 781002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781021) by changing a digit.

781020 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 11 ways as a sum of consecutive naturals, for example, 1990 + ... + 2349.

2⁷⁸¹⁰²⁰ is an apocalyptic number.

It is an amenable number.

781020 is an abundant number, since it is smaller than the sum of its proper divisors (1588620).

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

781020 is a wasteful number, since it uses less digits than its factorization.

781020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4354 (or 4349 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 781020 is about 883.7533592581. The cubic root of 781020 is about 92.0917484216.

The spelling of 781020 in words is "seven hundred eighty-one thousand, twenty".