780391 has 4 divisors (see below), whose sum is σ = 785232. Its totient is φ = 775552.

The previous prime is 780389. The next prime is 780397. The reversal of 780391 is 193087.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 193087 = 293 ⋅659.

It is a cyclic number.

It is not a de Polignac number, because 780391 - 2¹ = 780389 is a prime.

It is a super-2 number, since 2×780391² = 1218020225762, which contains 22 as substring.

It is a Duffinian number.

780391 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (780397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2170 + ... + 2503.

It is an arithmetic number, because the mean of its divisors is an integer number (196308).

2⁷⁸⁰³⁹¹ is an apocalyptic number.

780391 is a deficient number, since it is larger than the sum of its proper divisors (4841).

780391 is a wasteful number, since it uses less digits than its factorization.

780391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4840.

The product of its (nonzero) digits is 1512, while the sum is 28.

The square root of 780391 is about 883.3974190589. The cubic root of 780391 is about 92.0670195342.

The spelling of 780391 in words is "seven hundred eighty thousand, three hundred ninety-one".