1666555155 has 20 divisors (see below), whose sum is σ = 2987455152. Its totient is φ = 888829200.

The previous prime is 1666555129. The next prime is 1666555199. The reversal of 1666555155 is 5515556661.

It is not a de Polignac number, because 1666555155 - 2⁸ = 1666554899 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 1666555155.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2057071 + ... + 2057880.

Almost surely, 2^1666555155 is an apocalyptic number.

1666555155 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1666555155 is a deficient number, since it is larger than the sum of its proper divisors (1320899997).

1666555155 is an equidigital number, since it uses as much as digits as its factorization.

1666555155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4114968 (or 4114959 counting only the distinct ones).

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

The square root of 1666555155 is about 40823.4632901228. The cubic root of 1666555155 is about 1185.6046585669.

The spelling of 1666555155 in words is "one billion, six hundred sixty-six million, five hundred fifty-five thousand, one hundred fifty-five".