665749784 has 64 divisors (see below), whose sum is σ = 1516838400. Its totient is φ = 267416064.

The previous prime is 665749757. The next prime is 665749793. The reversal of 665749784 is 487947566.

Together with 851088615 it forms a betrothed pair.

It is a Harshad number since it is a multiple of its sum of digits (56).

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, 249047 + ... + 251705.

It is an arithmetic number, because the mean of its divisors is an integer number (23700600).

Almost surely, 2^665749784 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 665749784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (758419200).

665749784 is an abundant number, since it is smaller than the sum of its proper divisors (851088616).

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

665749784 is a wasteful number, since it uses less digits than its factorization.

665749784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2952 (or 2948 counting only the distinct ones).

The product of its digits is 10160640, while the sum is 56.

The square root of 665749784 is about 25802.1275091803. The cubic root of 665749784 is about 873.1797956038.

The spelling of 665749784 in words is "six hundred sixty-five million, seven hundred forty-nine thousand, seven hundred eighty-four".