1781920 has 96 divisors (see below), whose sum is σ = 5056128. Its totient is φ = 580608.

The previous prime is 1781903. The next prime is 1781921. The reversal of 1781920 is 291871.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (1781921) 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, 41419 + ... + 41461.

It is an arithmetic number, because the mean of its divisors is an integer number (52668).

2^1781920 is an apocalyptic number.

1781920 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 1781920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2528064).

1781920 is an abundant number, since it is smaller than the sum of its proper divisors (3274208).

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

1781920 is a wasteful number, since it uses less digits than its factorization.

1781920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102 (or 94 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 1781920 is about 1334.8857629026. The cubic root of 1781920 is about 121.2353863423.

It can be divided in two parts, 1781 and 920, that added together give a triangular number (2701 = T₇₃).

The spelling of 1781920 in words is "one million, seven hundred eighty-one thousand, nine hundred twenty".