221154661665 has 160 divisors (see below), whose sum is σ = 504976792320. Its totient is φ = 90143870976.

The previous prime is 221154661657. The next prime is 221154661669. The reversal of 221154661665 is 566166451122.

221154661665 is a `hidden beast` number, since 2 + 2 + 115 + 466 + 16 + 65 = 666.

It is not a de Polignac number, because 221154661665 - 2³ = 221154661657 is a prime.

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 221154661665.

It is not an unprimeable number, because it can be changed into a prime (221154661669) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 794949 + ... + 1036461.

It is an arithmetic number, because the mean of its divisors is an integer number (3156104952).

Almost surely, 2^221154661665 is an apocalyptic number.

It is an amenable number.

221154661665 is an abundant number, since it is smaller than the sum of its proper divisors (283822130655).

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

221154661665 is a wasteful number, since it uses less digits than its factorization.

221154661665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241573 (or 241564 counting only the distinct ones).

The product of its digits is 518400, while the sum is 45.

The spelling of 221154661665 in words is "two hundred twenty-one billion, one hundred fifty-four million, six hundred sixty-one thousand, six hundred sixty-five".