16661211215123 has 4 divisors (see below), whose sum is σ = 16664158542768. Its totient is φ = 16658263887480.

The previous prime is 16661211215107. The next prime is 16661211215141. The reversal of 16661211215123 is 32151211216661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16661211215123 - 2⁴ = 16661211215107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16661211215323) 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, 1473655343 + ... + 1473666648.

It is an arithmetic number, because the mean of its divisors is an integer number (4166039635692).

Almost surely, 2^{16661211215123} is an apocalyptic number.

16661211215123 is a deficient number, since it is larger than the sum of its proper divisors (2947327645).

16661211215123 is an equidigital number, since it uses as much as digits as its factorization.

16661211215123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2947327644.

The product of its digits is 25920, while the sum is 38.

The spelling of 16661211215123 in words is "sixteen trillion, six hundred sixty-one billion, two hundred eleven million, two hundred fifteen thousand, one hundred twenty-three".