1781940 has 48 divisors (see below), whose sum is σ = 5285952. Its totient is φ = 446976.

The previous prime is 1781939. The next prime is 1781981. The reversal of 1781940 is 491871.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1781898 and 1781907.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 147 + ... + 1893.

It is an arithmetic number, because the mean of its divisors is an integer number (110124).

2^1781940 is an apocalyptic number.

1781940 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1781940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2642976).

1781940 is an abundant number, since it is smaller than the sum of its proper divisors (3504012).

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

1781940 is a wasteful number, since it uses less digits than its factorization.

1781940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1776 (or 1774 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 1781940 is about 1334.8932541593. The cubic root of 1781940 is about 121.2358399165.

The spelling of 1781940 in words is "one million, seven hundred eighty-one thousand, nine hundred forty".