21715217166 has 16 divisors (see below), whose sum is σ = 43432283088. Its totient is φ = 7238097600.

The previous prime is 21715217137. The next prime is 21715217177. The reversal of 21715217166 is 66171251712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110956 + ... + 236096.

It is an arithmetic number, because the mean of its divisors is an integer number (2714517693).

Almost surely, 2^21715217166 is an apocalyptic number.

21715217166 is an abundant number, since it is smaller than the sum of its proper divisors (21717065922).

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

21715217166 is a wasteful number, since it uses less digits than its factorization.

21715217166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154067.

The product of its digits is 35280, while the sum is 39.

Adding to 21715217166 its reverse (66171251712), we get a palindrome (87886468878).

The spelling of 21715217166 in words is "twenty-one billion, seven hundred fifteen million, two hundred seventeen thousand, one hundred sixty-six".