781660 has 72 divisors (see below), whose sum is σ = 2010960. Its totient is φ = 253440.

The previous prime is 781633. The next prime is 781661. The reversal of 781660 is 66187.

It is a super-2 number, since 2×781660² = 1221984711200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781661) 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 23 ways as a sum of consecutive naturals, for example, 41131 + ... + 41149.

It is an arithmetic number, because the mean of its divisors is an integer number (27930).

2⁷⁸¹⁶⁶⁰ 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 781660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1005480).

781660 is an abundant number, since it is smaller than the sum of its proper divisors (1229300).

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

781660 is a wasteful number, since it uses less digits than its factorization.

781660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 781660 is about 884.1153770860. The cubic root of 781660 is about 92.1168961461.

It can be divided in two parts, 781 and 660, that added together give a palindrome (1441).

The spelling of 781660 in words is "seven hundred eighty-one thousand, six hundred sixty".