781310640 has 80 divisors (see below), whose sum is σ = 2642259456. Its totient is φ = 189408000.

The previous prime is 781310603. The next prime is 781310641. The reversal of 781310640 is 46013187.

It is a happy number.

781310640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×781310640² = 1220892632354419200, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 781310598 and 781310607.

It is not an unprimeable number, because it can be changed into a prime (781310641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 145336 + ... + 150615.

Almost surely, 2^781310640 is an apocalyptic number.

It is an amenable number.

781310640 is an abundant number, since it is smaller than the sum of its proper divisors (1860948816).

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

781310640 is a wasteful number, since it uses less digits than its factorization.

781310640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295978 (or 295972 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 781310640 is about 27951.9344589959. The cubic root of 781310640 is about 921.0317033417.

The spelling of 781310640 in words is "seven hundred eighty-one million, three hundred ten thousand, six hundred forty".