221205215455 has 16 divisors (see below), whose sum is σ = 303386771520. Its totient is φ = 151673766912.

The previous prime is 221205215423. The next prime is 221205215513. The reversal of 221205215455 is 554512502122.

It is a cyclic number.

It is not a de Polignac number, because 221205215455 - 2⁵ = 221205215423 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221205215455.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 367081 + ... + 759709.

It is an arithmetic number, because the mean of its divisors is an integer number (18961673220).

Almost surely, 2^221205215455 is an apocalyptic number.

221205215455 is a deficient number, since it is larger than the sum of its proper divisors (82181556065).

221205215455 is a wasteful number, since it uses less digits than its factorization.

221205215455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408738.

The product of its (nonzero) digits is 40000, while the sum is 34.

Adding to 221205215455 its reverse (554512502122), we get a palindrome (775717717577).

The spelling of 221205215455 in words is "two hundred twenty-one billion, two hundred five million, two hundred fifteen thousand, four hundred fifty-five".