205155122221 has 12 divisors (see below), whose sum is σ = 245099833788. Its totient is φ = 171094617792.

The previous prime is 205155122219. The next prime is 205155122281. The reversal of 205155122221 is 122221551502.

It can be written as a sum of positive squares in 2 ways, for example, as 179678493225 + 25476628996 = 423885^2 + 159614^2 .

It is not a de Polignac number, because 205155122221 - 2¹ = 205155122219 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 205155122221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205155122281) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56577096 + ... + 56580721.

It is an arithmetic number, because the mean of its divisors is an integer number (20424986149).

Almost surely, 2^205155122221 is an apocalyptic number.

It is an amenable number.

205155122221 is a deficient number, since it is larger than the sum of its proper divisors (39944711567).

205155122221 is a wasteful number, since it uses less digits than its factorization.

205155122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113157868 (or 113157861 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 28.

Adding to 205155122221 its reverse (122221551502), we get a palindrome (327376673723).

The spelling of 205155122221 in words is "two hundred five billion, one hundred fifty-five million, one hundred twenty-two thousand, two hundred twenty-one".