665547638 has 16 divisors (see below), whose sum is σ = 1171775904. Its totient is φ = 277525440.

The previous prime is 665547613. The next prime is 665547647. The reversal of 665547638 is 836745566.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 641903 + ... + 642938.

It is an arithmetic number, because the mean of its divisors is an integer number (73235994).

Almost surely, 2^665547638 is an apocalyptic number.

665547638 is a deficient number, since it is larger than the sum of its proper divisors (506228266).

665547638 is a wasteful number, since it uses less digits than its factorization.

665547638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1284887.

The product of its digits is 3628800, while the sum is 50.

The square root of 665547638 is about 25798.2099766631. The cubic root of 665547638 is about 873.0914102098.

The spelling of 665547638 in words is "six hundred sixty-five million, five hundred forty-seven thousand, six hundred thirty-eight".