1666640125 has 8 divisors (see below), whose sum is σ = 2079967032. Its totient is φ = 1333312000.

The previous prime is 1666640123. The next prime is 1666640141. The reversal of 1666640125 is 5210466661.

It can be written as a sum of positive squares in 4 ways, for example, as 16818201 + 1649821924 = 4101^2 + 40618^2 .

It is not a de Polignac number, because 1666640125 - 2¹ = 1666640123 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666640123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6666436 + ... + 6666685.

It is an arithmetic number, because the mean of its divisors is an integer number (259995879).

Almost surely, 2^1666640125 is an apocalyptic number.

It is an amenable number.

1666640125 is a deficient number, since it is larger than the sum of its proper divisors (413326907).

1666640125 is an equidigital number, since it uses as much as digits as its factorization.

1666640125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13333136 (or 13333126 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 1666640125 is about 40824.5039773908. The cubic root of 1666640125 is about 1185.6248077382.

The spelling of 1666640125 in words is "one billion, six hundred sixty-six million, six hundred forty thousand, one hundred twenty-five".