781040 has 40 divisors (see below), whose sum is σ = 1958208. Its totient is φ = 288000.

The previous prime is 781021. The next prime is 781043. The reversal of 781040 is 40187.

781040 = 76² + 77² + ... + 140².

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×781040² = 1220046963200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781043) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 665 + ... + 1415.

2⁷⁸¹⁰⁴⁰ 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 781040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (979104).

781040 is an abundant number, since it is smaller than the sum of its proper divisors (1177168).

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

781040 is a wasteful number, since it uses less digits than its factorization.

781040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777 (or 771 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 781040 is about 883.7646745599. The cubic root of 781040 is about 92.0925344959.

The spelling of 781040 in words is "seven hundred eighty-one thousand, forty".