781220 has 48 divisors (see below), whose sum is σ = 1850688. Its totient is φ = 274560.

The previous prime is 781217. The next prime is 781229. The reversal of 781220 is 22187.

It is a super-2 number, since 2×781220² = 1220609376800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 781192 and 781201.

It is not an unprimeable number, because it can be changed into a prime (781229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11627 + ... + 11693.

It is an arithmetic number, because the mean of its divisors is an integer number (38556).

2⁷⁸¹²²⁰ 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 781220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (925344).

781220 is an abundant number, since it is smaller than the sum of its proper divisors (1069468).

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

781220 is a wasteful number, since it uses less digits than its factorization.

781220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 781220 is about 883.8665057575. The cubic root of 781220 is about 92.0996085608.

It can be divided in two parts, 781 and 220, that added together give a palindrome (1001).

The spelling of 781220 in words is "seven hundred eighty-one thousand, two hundred twenty".