665604638 has 16 divisors (see below), whose sum is σ = 1058073840. Its totient is φ = 312948096.

The previous prime is 665604629. The next prime is 665604679. The reversal of 665604638 is 836406566.

665604638 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×665604638² = 886059068254222088, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33173 + ... + 49311.

It is an arithmetic number, because the mean of its divisors is an integer number (66129615).

Almost surely, 2^665604638 is an apocalyptic number.

665604638 is a deficient number, since it is larger than the sum of its proper divisors (392469202).

665604638 is a wasteful number, since it uses less digits than its factorization.

665604638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17371.

The product of its (nonzero) digits is 622080, while the sum is 44.

The square root of 665604638 is about 25799.3146808205. The cubic root of 665604638 is about 873.1163344410.

The spelling of 665604638 in words is "six hundred sixty-five million, six hundred four thousand, six hundred thirty-eight".