781281648 has 240 divisors, whose sum is σ = 2674114560. Its totient is φ = 207857664.

The previous prime is 781281647. The next prime is 781281671. The reversal of 781281648 is 846182187.

It is a super-2 number, since 2×781281648² = 1220802027003191808, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781281643) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2176093 + ... + 2176451.

It is an arithmetic number, because the mean of its divisors is an integer number (11142144).

Almost surely, 2^781281648 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 781281648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1337057280).

781281648 is an abundant number, since it is smaller than the sum of its proper divisors (1892832912).

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

781281648 is a wasteful number, since it uses less digits than its factorization.

781281648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524 (or 515 counting only the distinct ones).

The product of its digits is 172032, while the sum is 45.

The square root of 781281648 is about 27951.4158496488. The cubic root of 781281648 is about 921.0203109966.

The spelling of 781281648 in words is "seven hundred eighty-one million, two hundred eighty-one thousand, six hundred forty-eight".