2179553221561 has 9 divisors (see below), whose sum is σ = 2315330602351. Its totient is φ = 2051320587232.

The previous prime is 2179553221537. The next prime is 2179553221621. The reversal of 2179553221561 is 1651223559712.

The square root of 2179553221561 is 1476331.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1696883996025 + 482669225536 = 1302645^2 + 694744^2 .

It is not a de Polignac number, because 2179553221561 - 2⁹ = 2179553221049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2179553221861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 25054206 + ... + 25141048.

Almost surely, 2^{2179553221561} is an apocalyptic number.

2179553221561 is the 1476331-st square number.

2179553221561 is the 738166-th centered octagonal number.

It is an amenable number.

2179553221561 is a deficient number, since it is larger than the sum of its proper divisors (135777380790).

2179553221561 is an frugal number, since it uses more digits than its factorization.

2179553221561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173720 (or 86860 counting only the distinct ones).

The product of its digits is 1134000, while the sum is 49.

Multiplying 2179553221561 by its sum of digits (49), we get a square (106798107856489 = 10334317²).

The spelling of 2179553221561 in words is "two trillion, one hundred seventy-nine billion, five hundred fifty-three million, two hundred twenty-one thousand, five hundred sixty-one".