1556666 has 4 divisors (see below), whose sum is σ = 2335002. Its totient is φ = 778332.

The previous prime is 1556657. The next prime is 1556669. The reversal of 1556666 is 6666551.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1510441 + 46225 = 1229^2 + 215^2 .

It is a Curzon number.

It is a plaindrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (1556669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389165 + ... + 389168.

2^1556666 is an apocalyptic number.

1556666 is a deficient number, since it is larger than the sum of its proper divisors (778336).

1556666 is an equidigital number, since it uses as much as digits as its factorization.

1556666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778335.

The product of its digits is 32400, while the sum is 35.

The square root of 1556666 is about 1247.6642176483. The cubic root of 1556666 is about 115.8951192321.

It can be divided in two parts, 1556 and 666, that added together give a palindrome (2222).

The spelling of 1556666 in words is "one million, five hundred fifty-six thousand, six hundred sixty-six".