1781990340 has 96 divisors (see below), whose sum is σ = 5415997440. Its totient is φ = 435165696.

The previous prime is 1781990333. The next prime is 1781990359. The reversal of 1781990340 is 430991871.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 1781990292 and 1781990301.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 90066 + ... + 108054.

It is an arithmetic number, because the mean of its divisors is an integer number (56416640).

Almost surely, 2^1781990340 is an apocalyptic number.

1781990340 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 1781990340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2707998720).

1781990340 is an abundant number, since it is smaller than the sum of its proper divisors (3634007100).

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

1781990340 is a wasteful number, since it uses less digits than its factorization.

1781990340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18141 (or 18139 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 1781990340 is about 42213.6274205380. The cubic root of 1781990340 is about 1212.3698154768.

The spelling of 1781990340 in words is "one billion, seven hundred eighty-one million, nine hundred ninety thousand, three hundred forty".