9781664 has 24 divisors (see below), whose sum is σ = 20391588. Its totient is φ = 4602880.

The previous prime is 9781661. The next prime is 9781697. The reversal of 9781664 is 4661879.

It can be written as a sum of positive squares in 2 ways, for example, as 7507600 + 2274064 = 2740^2 + 1508^2 .

It is not an unprimeable number, because it can be changed into a prime (9781661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8447 + ... + 9534.

Almost surely, 2^9781664 is an apocalyptic number.

It is an amenable number.

9781664 is an abundant number, since it is smaller than the sum of its proper divisors (10609924).

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

9781664 is a wasteful number, since it uses less digits than its factorization.

9781664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18008 (or 18000 counting only the distinct ones).

The product of its digits is 72576, while the sum is 41.

The square root of 9781664 is about 3127.5651871704. The cubic root of 9781664 is about 213.8639482272.

The spelling of 9781664 in words is "nine million, seven hundred eighty-one thousand, six hundred sixty-four".