16660121 has 4 divisors (see below), whose sum is σ = 16694544. Its totient is φ = 16625700.

The previous prime is 16660109. The next prime is 16660151. The reversal of 16660121 is 12106661.

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: 12106661 = 7 ⋅1729523.

It is a cyclic number.

It is not a de Polignac number, because 16660121 - 2⁶ = 16660057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16660151) 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, 16475 + ... + 17456.

It is an arithmetic number, because the mean of its divisors is an integer number (4173636).

Almost surely, 2^16660121 is an apocalyptic number.

It is an amenable number.

16660121 is a deficient number, since it is larger than the sum of its proper divisors (34423).

16660121 is an equidigital number, since it uses as much as digits as its factorization.

16660121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34422.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 16660121 is about 4081.6811487425. The cubic root of 16660121 is about 255.4030330451.

Adding to 16660121 its reverse (12106661), we get a palindrome (28766782).

The spelling of 16660121 in words is "sixteen million, six hundred sixty thousand, one hundred twenty-one".