1666121025 has 12 divisors (see below), whose sum is σ = 2754653552. Its totient is φ = 888597840.

The previous prime is 1666120997. The next prime is 1666121047. The reversal of 1666121025 is 5201216661.

It is not a de Polignac number, because 1666121025 - 2⁵ = 1666120993 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1666120983 and 1666121001.

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 11 ways as a sum of consecutive naturals, for example, 11107399 + ... + 11107548.

Almost surely, 2^1666121025 is an apocalyptic number.

1666121025 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1666121025 is a deficient number, since it is larger than the sum of its proper divisors (1088532527).

1666121025 is a wasteful number, since it uses less digits than its factorization.

1666121025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22214960 (or 22214955 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 1666121025 is about 40818.1457810126. The cubic root of 1666121025 is about 1185.5017014284.

Adding to 1666121025 its reverse (5201216661), we get a palindrome (6867337686).

The spelling of 1666121025 in words is "one billion, six hundred sixty-six million, one hundred twenty-one thousand, twenty-five".