666111555 has 24 divisors (see below), whose sum is σ = 1185801552. Its totient is φ = 345657024.

The previous prime is 666111553. The next prime is 666111559. The reversal of 666111555 is 555111666.

It is not a de Polignac number, because 666111555 - 2¹ = 666111553 is a prime.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (666111553) 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, 198369 + ... + 201698.

It is an arithmetic number, because the mean of its divisors is an integer number (49408398).

Almost surely, 2^666111555 is an apocalyptic number.

666111555 is a deficient number, since it is larger than the sum of its proper divisors (519689997).

666111555 is a wasteful number, since it uses less digits than its factorization.

666111555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400115 (or 400112 counting only the distinct ones).

The product of its digits is 27000, while the sum is 36.

The square root of 666111555 is about 25809.1370448529. The cubic root of 666111555 is about 873.3379300530.

It can be divided in two parts, 666111 and 555, that added together give a palindrome (666666).

The spelling of 666111555 in words is "six hundred sixty-six million, one hundred eleven thousand, five hundred fifty-five".