1666205540 has 12 divisors (see below), whose sum is σ = 3499031676. Its totient is φ = 666482208.

The previous prime is 1666205533. The next prime is 1666205549. The reversal of 1666205540 is 455026661.

It can be written as a sum of positive squares in 2 ways, for example, as 368332864 + 1297872676 = 19192^2 + 36026^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1666205540.

It is not an unprimeable number, because it can be changed into a prime (1666205549) 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 3 ways as a sum of consecutive naturals, for example, 41655119 + ... + 41655158.

It is an arithmetic number, because the mean of its divisors is an integer number (291585973).

Almost surely, 2^1666205540 is an apocalyptic number.

1666205540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1666205540 is an abundant number, since it is smaller than the sum of its proper divisors (1832826136).

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

1666205540 is a wasteful number, since it uses less digits than its factorization.

1666205540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83310286 (or 83310284 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The square root of 1666205540 is about 40819.1810304910. The cubic root of 1666205540 is about 1185.5217461872.

The spelling of 1666205540 in words is "one billion, six hundred sixty-six million, two hundred five thousand, five hundred forty".