1781779842 has 40 divisors (see below), whose sum is σ = 4010024700. Its totient is φ = 591320736.

The previous prime is 1781779829. The next prime is 1781779849. The reversal of 1781779842 is 2489771871.

It can be written as a sum of positive squares in 2 ways, for example, as 1668804201 + 112975641 = 40851^2 + 10629^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (1781779849) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 13084 + ... + 61112.

Almost surely, 2^1781779842 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1781779842, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2005012350).

1781779842 is an abundant number, since it is smaller than the sum of its proper divisors (2228244858).

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

1781779842 is a wasteful number, since it uses less digits than its factorization.

1781779842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48272 (or 48263 counting only the distinct ones).

The product of its digits is 1580544, while the sum is 54.

The square root of 1781779842 is about 42211.1340999031. The cubic root of 1781779842 is about 1212.3220764469.

The spelling of 1781779842 in words is "one billion, seven hundred eighty-one million, seven hundred seventy-nine thousand, eight hundred forty-two".