21166235205 has 16 divisors (see below), whose sum is σ = 33867884160. Its totient is φ = 11288022848.

The previous prime is 21166235197. The next prime is 21166235297. The reversal of 21166235205 is 50253266112.

It is a cyclic number.

It is not a de Polignac number, because 21166235205 - 2³ = 21166235197 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 375019 + ... + 427751.

It is an arithmetic number, because the mean of its divisors is an integer number (2116742760).

Almost surely, 2^21166235205 is an apocalyptic number.

It is an amenable number.

21166235205 is a deficient number, since it is larger than the sum of its proper divisors (12701648955).

21166235205 is a wasteful number, since it uses less digits than its factorization.

21166235205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79500.

The product of its (nonzero) digits is 21600, while the sum is 33.

The spelling of 21166235205 in words is "twenty-one billion, one hundred sixty-six million, two hundred thirty-five thousand, two hundred five".