9781780 has 48 divisors (see below), whose sum is σ = 21450240. Its totient is φ = 3744000.

The previous prime is 9781763. The next prime is 9781823. The reversal of 9781780 is 871879.

It is an Ulam number.

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, 64705 + ... + 64855.

It is an arithmetic number, because the mean of its divisors is an integer number (446880).

Almost surely, 2^9781780 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 9781780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10725120).

9781780 is an abundant number, since it is smaller than the sum of its proper divisors (11668460).

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

9781780 is a wasteful number, since it uses less digits than its factorization.

9781780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280 (or 278 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 40.

The square root of 9781780 is about 3127.5837318927. The cubic root of 9781780 is about 213.8647936226.

The spelling of 9781780 in words is "nine million, seven hundred eighty-one thousand, seven hundred eighty".