781660656 has 120 divisors (see below), whose sum is σ = 2528454240. Its totient is φ = 220796928.

The previous prime is 781660643. The next prime is 781660661. The reversal of 781660656 is 656066187.

It is a super-2 number, since 2×781660656² = 1221986762276700672, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 85356 + ... + 94068.

It is an arithmetic number, because the mean of its divisors is an integer number (21070452).

Almost surely, 2^781660656 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 781660656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1264227120).

781660656 is an abundant number, since it is smaller than the sum of its proper divisors (1746793584).

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

781660656 is a wasteful number, since it uses less digits than its factorization.

781660656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8823 (or 8814 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The square root of 781660656 is about 27958.1947915097. The cubic root of 781660656 is about 921.1692191552.

The spelling of 781660656 in words is "seven hundred eighty-one million, six hundred sixty thousand, six hundred fifty-six".