665945826 has 64 divisors (see below), whose sum is σ = 1660108800. Its totient is φ = 173399616.

The previous prime is 665945809. The next prime is 665945857. The reversal of 665945826 is 628549566.

665945826 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 35415 + ... + 50853.

It is an arithmetic number, because the mean of its divisors is an integer number (25939200).

Almost surely, 2^665945826 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665945826, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (830054400).

665945826 is an abundant number, since it is smaller than the sum of its proper divisors (994162974).

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

665945826 is a wasteful number, since it uses less digits than its factorization.

665945826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15543.

The product of its digits is 3110400, while the sum is 51.

The square root of 665945826 is about 25805.9261798526. The cubic root of 665945826 is about 873.2654950252.

The spelling of 665945826 in words is "six hundred sixty-five million, nine hundred forty-five thousand, eight hundred twenty-six".