21661722216167 has 4 divisors (see below), whose sum is σ = 23630969690376. Its totient is φ = 19692474741960.

The previous prime is 21661722216163. The next prime is 21661722216217. The reversal of 21661722216167 is 76161222716612.

It is a happy number.

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 21661722216167 - 2² = 21661722216163 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661722216161) 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, 984623737088 + ... + 984623737109.

It is an arithmetic number, because the mean of its divisors is an integer number (5907742422594).

Almost surely, 2^{21661722216167} is an apocalyptic number.

21661722216167 is a deficient number, since it is larger than the sum of its proper divisors (1969247474209).

21661722216167 is a wasteful number, since it uses less digits than its factorization.

21661722216167 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1969247474208.

The product of its digits is 1016064, while the sum is 50.

The spelling of 21661722216167 in words is "twenty-one trillion, six hundred sixty-one billion, seven hundred twenty-two million, two hundred sixteen thousand, one hundred sixty-seven".