781915680 has 864 divisors, whose sum is σ = 3625824384. Its totient is φ = 155271168.

The previous prime is 781915679. The next prime is 781915681. The reversal of 781915680 is 86519187.

781915680 is a `hidden beast` number, since 7 + 81 + 9 + 1 + 568 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (781915679) and next prime (781915681).

It is a tau number, because it is divible by the number of its divisors (864).

It is a super-2 number, since 2×781915680² = 1222784261259724800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781915681) by changing a digit.

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 143 ways as a sum of consecutive naturals, for example, 45995032 + ... + 45995048.

It is an arithmetic number, because the mean of its divisors is an integer number (4196556).

Almost surely, 2^781915680 is an apocalyptic number.

781915680 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 781915680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1812912192).

781915680 is an abundant number, since it is smaller than the sum of its proper divisors (2843908704).

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

781915680 is a wasteful number, since it uses less digits than its factorization.

781915680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 45.

The square root of 781915680 is about 27962.7552290542. The cubic root of 781915680 is about 921.2693882475.

The spelling of 781915680 in words is "seven hundred eighty-one million, nine hundred fifteen thousand, six hundred eighty".