781621344 has 216 divisors, whose sum is σ = 2616862248. Its totient is φ = 220631040.

The previous prime is 781621303. The next prime is 781621367. The reversal of 781621344 is 443126187.

It is a super-2 number, since 2×781621344² = 1221863850792732672, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 781621299 and 781621308.

It is a congruent number.

It is an unprimeable 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 35 ways as a sum of consecutive naturals, for example, 1368579 + ... + 1369149.

It is an arithmetic number, because the mean of its divisors is an integer number (12115103).

Almost surely, 2^781621344 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 781621344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1308431124).

781621344 is an abundant number, since it is smaller than the sum of its proper divisors (1835240904).

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

781621344 is a wasteful number, since it uses less digits than its factorization.

781621344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 698 (or 680 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 781621344 is about 27957.4917329863. The cubic root of 781621344 is about 921.1537761318.

The spelling of 781621344 in words is "seven hundred eighty-one million, six hundred twenty-one thousand, three hundred forty-four".