2051221551205 has 4 divisors (see below), whose sum is σ = 2461465861452. Its totient is φ = 1640977240960.

The previous prime is 2051221551179. The next prime is 2051221551217. The reversal of 2051221551205 is 5021551221502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1109362947169 + 941858604036 = 1053263^2 + 970494^2 .

It is a de Polignac number, because none of the positive numbers 2^k-2051221551205 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 205122155116 + ... + 205122155125.

It is an arithmetic number, because the mean of its divisors is an integer number (615366465363).

Almost surely, 2^{2051221551205} is an apocalyptic number.

It is an amenable number.

2051221551205 is a deficient number, since it is larger than the sum of its proper divisors (410244310247).

2051221551205 is an equidigital number, since it uses as much as digits as its factorization.

2051221551205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410244310246.

The product of its (nonzero) digits is 10000, while the sum is 31.

Adding to 2051221551205 its reverse (5021551221502), we get a palindrome (7072772772707).

The spelling of 2051221551205 in words is "two trillion, fifty-one billion, two hundred twenty-one million, five hundred fifty-one thousand, two hundred five".