781648 has 30 divisors (see below), whose sum is σ = 1763466. Its totient is φ = 334656.

The previous prime is 781633. The next prime is 781661. The reversal of 781648 is 846187.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 753424 + 28224 = 868^2 + 168^2 .

It is a super-2 number, since 2×781648² = 1221947191808, which contains 22 as substring.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

781648 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 286 + ... + 1282.

2⁷⁸¹⁶⁴⁸ 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 781648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (881733).

781648 is an abundant number, since it is smaller than the sum of its proper divisors (981818).

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

781648 is a wasteful number, since it uses less digits than its factorization.

781648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1019 (or 1006 counting only the distinct ones).

The product of its digits is 10752, while the sum is 34.

The square root of 781648 is about 884.1085906154. The cubic root of 781648 is about 92.1164247526.

It can be divided in two parts, 7 and 81648, that multiplied together give a square (571536 = 756²).

The spelling of 781648 in words is "seven hundred eighty-one thousand, six hundred forty-eight".