21210556166 has 8 divisors (see below), whose sum is σ = 31827242064. Its totient is φ = 10601475480.

The previous prime is 21210556153. The next prime is 21210556201. The reversal of 21210556166 is 66165501212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1894325 + ... + 1905488.

It is an arithmetic number, because the mean of its divisors is an integer number (3978405258).

Almost surely, 2^21210556166 is an apocalyptic number.

21210556166 is a deficient number, since it is larger than the sum of its proper divisors (10616685898).

21210556166 is a wasteful number, since it uses less digits than its factorization.

21210556166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3802606.

The product of its (nonzero) digits is 21600, while the sum is 35.

The spelling of 21210556166 in words is "twenty-one billion, two hundred ten million, five hundred fifty-six thousand, one hundred sixty-six".