781680 has 40 divisors (see below), whose sum is σ = 2423952. Its totient is φ = 208384.

The previous prime is 781673. The next prime is 781681. The reversal of 781680 is 86187.

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

It is a super-2 number, since 2×781680² = 1222047244800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781681) by changing a digit.

781680 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 7 ways as a sum of consecutive naturals, for example, 1389 + ... + 1868.

2⁷⁸¹⁶⁸⁰ is an apocalyptic number.

It is an amenable number.

781680 is an abundant number, since it is smaller than the sum of its proper divisors (1642272).

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

781680 is a wasteful number, since it uses less digits than its factorization.

781680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3273 (or 3267 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 781680 is about 884.1266877546. The cubic root of 781680 is about 92.1176817913.

The spelling of 781680 in words is "seven hundred eighty-one thousand, six hundred eighty".