666551555 has 32 divisors (see below), whose sum is σ = 872944128. Its totient is φ = 486604800.

The previous prime is 666551551. The next prime is 666551591. The reversal of 666551555 is 555155666.

666551555 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 666551555 - 2² = 666551551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666551551) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 672110 + ... + 673100.

It is an arithmetic number, because the mean of its divisors is an integer number (27279504).

Almost surely, 2^666551555 is an apocalyptic number.

666551555 is a deficient number, since it is larger than the sum of its proper divisors (206392573).

666551555 is a wasteful number, since it uses less digits than its factorization.

666551555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1247.

The product of its digits is 675000, while the sum is 44.

The square root of 666551555 is about 25817.6597506436. The cubic root of 666551555 is about 873.5301821905.

The spelling of 666551555 in words is "six hundred sixty-six million, five hundred fifty-one thousand, five hundred fifty-five".