21717055665 has 32 divisors (see below), whose sum is σ = 38733932160. Its totient is φ = 11544679872.

The previous prime is 21717055663. The next prime is 21717055669. The reversal of 21717055665 is 56655071712.

21717055665 is a `hidden beast` number, since 2 + 17 + 1 + 70 + 5 + 566 + 5 = 666.

It is not a de Polignac number, because 21717055665 - 2¹ = 21717055663 is a prime.

It is a super-3 number, since 3×21717055665³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21717055665.

It is not an unprimeable number, because it can be changed into a prime (21717055663) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 220554 + ... + 303443.

It is an arithmetic number, because the mean of its divisors is an integer number (1210435380).

Almost surely, 2^21717055665 is an apocalyptic number.

It is an amenable number.

21717055665 is a deficient number, since it is larger than the sum of its proper divisors (17016876495).

21717055665 is a wasteful number, since it uses less digits than its factorization.

21717055665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524318 (or 524312 counting only the distinct ones).

The product of its (nonzero) digits is 441000, while the sum is 45.

The spelling of 21717055665 in words is "twenty-one billion, seven hundred seventeen million, fifty-five thousand, six hundred sixty-five".