665540871 has 8 divisors (see below), whose sum is σ = 939587184. Its totient is φ = 417594240.

The previous prime is 665540851. The next prime is 665540881. The reversal of 665540871 is 178045566.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 665540871 - 2¹⁴ = 665524487 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665540831) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6524860 + ... + 6524961.

It is an arithmetic number, because the mean of its divisors is an integer number (117448398).

Almost surely, 2^665540871 is an apocalyptic number.

665540871 is a deficient number, since it is larger than the sum of its proper divisors (274046313).

665540871 is a wasteful number, since it uses less digits than its factorization.

665540871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13049841.

The product of its (nonzero) digits is 201600, while the sum is 42.

The square root of 665540871 is about 25798.0788238194. The cubic root of 665540871 is about 873.0884511280.

The spelling of 665540871 in words is "six hundred sixty-five million, five hundred forty thousand, eight hundred seventy-one".