666081558 has 24 divisors (see below), whose sum is σ = 1450740096. Its totient is φ = 220863600.

The previous prime is 666081553. The next prime is 666081569. The reversal of 666081558 is 855180666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666081553) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 93433 + ... + 100308.

It is an arithmetic number, because the mean of its divisors is an integer number (60447504).

Almost surely, 2^666081558 is an apocalyptic number.

666081558 is an abundant number, since it is smaller than the sum of its proper divisors (784658538).

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

666081558 is a wasteful number, since it uses less digits than its factorization.

666081558 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193940 (or 193937 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The square root of 666081558 is about 25808.5559069081. Note that the first 3 decimals coincide. The cubic root of 666081558 is about 873.3248201813.

The spelling of 666081558 in words is "six hundred sixty-six million, eighty-one thousand, five hundred fifty-eight".