1556601666 has 16 divisors (see below), whose sum is σ = 3116846304. Its totient is φ = 518260064.

The previous prime is 1556601643. The next prime is 1556601707. The reversal of 1556601666 is 6661066551.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 146220 + ... + 156503.

It is an arithmetic number, because the mean of its divisors is an integer number (194802894).

Almost surely, 2^1556601666 is an apocalyptic number.

1556601666 is an abundant number, since it is smaller than the sum of its proper divisors (1560244638).

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

1556601666 is a wasteful number, since it uses less digits than its factorization.

1556601666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303585.

The product of its (nonzero) digits is 194400, while the sum is 42.

The square root of 1556601666 is about 39453.7915288252. The cubic root of 1556601666 is about 1158.9352263629.

The spelling of 1556601666 in words is "one billion, five hundred fifty-six million, six hundred one thousand, six hundred sixty-six".