21166837766844 has 144 divisors (see below), whose sum is σ = 66362645260800. Its totient is φ = 5174475210240.

The previous prime is 21166837766839. The next prime is 21166837766849. The reversal of 21166837766844 is 44866773866112.

It is an interprime number because it is at equal distance from previous prime (21166837766839) and next prime (21166837766849).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21166837766849) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 96141444 + ... + 96361355.

It is an arithmetic number, because the mean of its divisors is an integer number (460851703200).

Almost surely, 2^{21166837766844} is an apocalyptic number.

It is an amenable number.

21166837766844 is an abundant number, since it is smaller than the sum of its proper divisors (45195807493956).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21166837766844 is a wasteful number, since it uses less digits than its factorization.

21166837766844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192502848 (or 192502839 counting only the distinct ones).

The product of its digits is 390168576, while the sum is 69.

The spelling of 21166837766844 in words is "twenty-one trillion, one hundred sixty-six billion, eight hundred thirty-seven million, seven hundred sixty-six thousand, eight hundred forty-four".