1997221859361 has 81 divisors (see below), whose sum is σ = 2999817973971. Its totient is φ = 1280455121088.

The previous prime is 1997221859359. The next prime is 1997221859363. The reversal of 1997221859361 is 1639581227991.

The square root of 1997221859361 is 1413231.

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

1997221859361 is a `hidden beast` number, since 1 + 9 + 9 + 7 + 2 + 218 + 59 + 361 = 666.

It is an interprime number because it is at equal distance from previous prime (1997221859359) and next prime (1997221859363).

It can be written as a sum of positive squares in only one way, i.e., 383508956961 + 1613712902400 = 619281^2 + 1270320^2 .

It is not a de Polignac number, because 1997221859361 - 2¹ = 1997221859359 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1997221859363) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 22440695005 + ... + 22440695093.

Almost surely, 2^{1997221859361} is an apocalyptic number.

1997221859361 is the 1413231-st square number.

1997221859361 is the 706616-th centered octagonal number.

It is an amenable number.

1997221859361 is a deficient number, since it is larger than the sum of its proper divisors (1002596114610).

1997221859361 is an frugal number, since it uses more digits than its factorization.

1997221859361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 476 (or 238 counting only the distinct ones).

The product of its digits is 14696640, while the sum is 63.

It can be divided in two parts, 1997221 and 859361, that added together give a palindrome (2856582).

The spelling of 1997221859361 in words is "one trillion, nine hundred ninety-seven billion, two hundred twenty-one million, eight hundred fifty-nine thousand, three hundred sixty-one".