21666672166667 has 32 divisors (see below), whose sum is σ = 25180132034304. Its totient is φ = 18424999756800.

The previous prime is 21666672166637. The next prime is 21666672166753. The reversal of 21666672166667 is 76666127666612.

It is a cyclic number.

It is not a de Polignac number, because 21666672166667 - 2¹⁰ = 21666672165643 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21666672166597 and 21666672166606.

It is not an unprimeable number, because it can be changed into a prime (21666672166637) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23378792 + ... + 24287882.

It is an arithmetic number, because the mean of its divisors is an integer number (786879126072).

Almost surely, 2^{21666672166667} is an apocalyptic number.

21666672166667 is a deficient number, since it is larger than the sum of its proper divisors (3513459867637).

21666672166667 is a wasteful number, since it uses less digits than its factorization.

21666672166667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 909899.

The product of its digits is 329204736, while the sum is 68.

Subtracting 21666672166667 from its reverse (76666127666612), we obtain a palindrome (54999455499945).

It can be divided in two parts, 2166667 and 2166667, that added together give a palindrome (4333334).

The spelling of 21666672166667 in words is "twenty-one trillion, six hundred sixty-six billion, six hundred seventy-two million, one hundred sixty-six thousand, six hundred sixty-seven".