781116580864 has 99 divisors (see below), whose sum is σ = 1587854508121. Its totient is φ = 384067604480.

The previous prime is 781116580861. The next prime is 781116580913. The reversal of 781116580864 is 468085611187.

The square root of 781116580864 is 883808.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 184391230464 + 596725350400 = 429408^2 + 772480^2 .

It is a super-2 number, since 2×781116580864² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (781116580861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2008011582 + ... + 2008011970.

Almost surely, 2^781116580864 is an apocalyptic number.

781116580864 is the 883808-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 781116580864

781116580864 is an abundant number, since it is smaller than the sum of its proper divisors (806737927257).

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

781116580864 is an frugal number, since it uses more digits than its factorization.

781116580864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 940 (or 462 counting only the distinct ones).

The product of its (nonzero) digits is 2580480, while the sum is 55.

The spelling of 781116580864 in words is "seven hundred eighty-one billion, one hundred sixteen million, five hundred eighty thousand, eight hundred sixty-four".