1666332121 has 4 divisors (see below), whose sum is σ = 1669900752. Its totient is φ = 1662763492.

The previous prime is 1666332077. The next prime is 1666332131. The reversal of 1666332121 is 1212336661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1212336661 = 59 ⋅20548079.

It is a cyclic number.

It is not a de Polignac number, because 1666332121 - 2⁹ = 1666331609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666332131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1783615 + ... + 1784548.

It is an arithmetic number, because the mean of its divisors is an integer number (417475188).

Almost surely, 2^1666332121 is an apocalyptic number.

It is an amenable number.

1666332121 is a deficient number, since it is larger than the sum of its proper divisors (3568631).

1666332121 is an equidigital number, since it uses as much as digits as its factorization.

1666332121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3568630.

The product of its digits is 7776, while the sum is 31.

The square root of 1666332121 is about 40820.7315098591. The cubic root of 1666332121 is about 1185.5517666388.

Adding to 1666332121 its reverse (1212336661), we get a palindrome (2878668782).

It can be divided in two parts, 16663 and 32121, that added together give a palindrome (48784).

The spelling of 1666332121 in words is "one billion, six hundred sixty-six million, three hundred thirty-two thousand, one hundred twenty-one".