21205166443 has 16 divisors (see below), whose sum is σ = 21581004960. Its totient is φ = 20833120000.

The previous prime is 21205166383. The next prime is 21205166447. The reversal of 21205166443 is 34466150212.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21205166443 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21205166399 and 21205166408.

It is not an unprimeable number, because it can be changed into a prime (21205166447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11153793 + ... + 11155693.

It is an arithmetic number, because the mean of its divisors is an integer number (1348812810).

Almost surely, 2^21205166443 is an apocalyptic number.

21205166443 is a deficient number, since it is larger than the sum of its proper divisors (375838517).

21205166443 is a wasteful number, since it uses less digits than its factorization.

21205166443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2798.

The product of its (nonzero) digits is 34560, while the sum is 34.

The spelling of 21205166443 in words is "twenty-one billion, two hundred five million, one hundred sixty-six thousand, four hundred forty-three".