665604639 has 24 divisors (see below), whose sum is σ = 1112022912. Its totient is φ = 375760080.

The previous prime is 665604629. The next prime is 665604679. The reversal of 665604639 is 936406566.

665604639 is a `hidden beast` number, since 6 + 6 + 5 + 6 + 0 + 4 + 639 = 666.

It is not a de Polignac number, because 665604639 - 2¹⁵ = 665571871 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 665604594 and 665604603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665604629) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 58417 + ... + 68874.

It is an arithmetic number, because the mean of its divisors is an integer number (46334288).

Almost surely, 2^665604639 is an apocalyptic number.

665604639 is a deficient number, since it is larger than the sum of its proper divisors (446418273).

665604639 is a wasteful number, since it uses less digits than its factorization.

665604639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127387 (or 127384 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 45.

The square root of 665604639 is about 25799.3147002009. The cubic root of 665604639 is about 873.1163348783.

The spelling of 665604639 in words is "six hundred sixty-five million, six hundred four thousand, six hundred thirty-nine".