1666515555 has 24 divisors (see below), whose sum is σ = 3040661520. Its totient is φ = 842028480.

The previous prime is 1666515553. The next prime is 1666515601. The reversal of 1666515555 is 5555156661.

It is not a de Polignac number, because 1666515555 - 2¹ = 1666515553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 1666515555.

It is not an unprimeable number, because it can be changed into a prime (1666515551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 973716 + ... + 975425.

It is an arithmetic number, because the mean of its divisors is an integer number (126694230).

Almost surely, 2^1666515555 is an apocalyptic number.

1666515555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1666515555 is a deficient number, since it is larger than the sum of its proper divisors (1374145965).

1666515555 is a wasteful number, since it uses less digits than its factorization.

1666515555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1949171 (or 1949168 counting only the distinct ones).

The product of its digits is 675000, while the sum is 45.

The square root of 1666515555 is about 40822.9782720467. The cubic root of 1666515555 is about 1185.5952678753.

The spelling of 1666515555 in words is "one billion, six hundred sixty-six million, five hundred fifteen thousand, five hundred fifty-five".