665567838 has 48 divisors (see below), whose sum is σ = 1560904800. Its totient is φ = 203746752.

The previous prime is 665567831. The next prime is 665567839. The reversal of 665567838 is 838765566.

665567838 is a `hidden beast` number, since 6 + 6 + 556 + 7 + 83 + 8 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665567831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 39420 + ... + 53712.

It is an arithmetic number, because the mean of its divisors is an integer number (32518850).

Almost surely, 2^665567838 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665567838, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (780452400).

665567838 is an abundant number, since it is smaller than the sum of its proper divisors (895336962).

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

665567838 is a wasteful number, since it uses less digits than its factorization.

665567838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14513 (or 14510 counting only the distinct ones).

The product of its digits is 7257600, while the sum is 54.

The square root of 665567838 is about 25798.6014737233. The cubic root of 665567838 is about 873.1002431703.

The spelling of 665567838 in words is "six hundred sixty-five million, five hundred sixty-seven thousand, eight hundred thirty-eight".